'I transferred $500k to the wrong vendor': 25 Expensive mistakes that people will never live down

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Remy Millisky • Writer and Editor
Mar 29, 2025 11:00 AM EDT

We all have that one financial choice we made that haunts us forever… and usually, there's nothing to be done about it. You're just left with a smaller amount of cash in your bank account and sadness in your heart. 

In a workplace setting, a costly mistake can put your job on the line. However, some people consider their biggest financial mistakes to be going to college for the wrong major, or investing time in a relationship that didn't work out. It's all about the timing of things… just tell that to the people who sold their properties for too little money, only to watch their (former) property value skyrocket a year or two later! Check out a bunch of interesting things that people consider to be their biggest and most expensive mistakes down below. 

Next, read about the 14-year-old stepsisters who can't agree on a basement renovation project, leading one of the girls to ruin it: 'My stepdaughter can't return home until she pays my daughter back.'

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  • 01
    'Made a calculation error at work... which led to the firm undercharging -$130k on a project'
    via Getty Images For Unsplash+

    The image does not depict the actual subjects of the story. Subjects are models.

  • 02

    "What is the most expensive mistake you have ever made?"

    EMH55 Wouldn't budge from $62,500 for a downtown loft. Owner wanted 65k. Unit sold for $275,000 1 year later.
    via u/EMH55
  • 03

    Infuriating

    halt_n_catch _... Rented a place for vacation, had to front half the money, but couldn't go.
    via u/halt__n__catch__fire
  • 04
    roustajoe For me, grad school. Realized I went for the wrong reasons about half way through the courses and decided that I should keep going so I wouldn't waste any money. I had a hard realization a few months after graduating that I could only survive paying
    via u/roustajoe
  • 05
    my loans back and not thrive. I relocated to the oilfield and have been working a niche job of a niche blue collar job ever since. After working in Temps from -43f to 105 I can finally say that I paid off my loans.
    via u/roustajoe
  • 06
    on... Trusting a moving company...cost me $1000, was a straight-up scam. The grand was my down- payment on a contract that accounted for all my stuff. A guy from a different company showed up and wanted a new contract with an extra ridiculous charge for my g in safe, and when I turned basically a random person away BECAUSE I
    via u/onebatch_twobatch
  • 07
    HAD NO REASON TO BELIEVE WHO HE WAS, the first guy stopped answering calls, claimed I turned away service, and kept my down- payment on those grounds. Their company said "yep" and my bank couldn't get the money back on a fraud claim. I fully believe that if I'd let the 2nd guy take my stuff, they'd have extorted me for thousands of extra dollars.
    via u/onebatch_twobatch
  • 08
    EmotionSilent682 Invested in a stock without doing proper research. Lost a lot of money.
    via u/EmotionSilent682
  • 09
    SupremeEmperor... I relied too much on others and became homeless when I lost my supports. That mistake cost me about 15 grand and I am still struggling to pay it off.
    via u/SupremeEmperorNoms
  • 10
    sews4dogs Not paying my car insurance on time. Then proceeding to slide through an icy intersection and hit another car. No one got hurt, just my wallet. Almost $7000
    via u/sews4dogs
  • 11
    squid 1891 Was troubleshooting an windshield de-icing test set used for F/A18's and had made an error in my set up. The error caused me to fry a non-procurable circuit card; leading to the entire test set, which was around $180k, to have to be replaced.
    via u/squid 1891
  • 12
    MrSuperFantastic A friend of mine was an early backer of Bitcoin. Tried to convince me to invest a $20K windfall I had into it. In 2013. I said no, crypto was dumb. Said friend now never has to work again.
    via u/MrSuperFantastic
  • 13
    noodlemom72 Signed onto a mortgage with my ex when I was 21 because he "just needed a little signature, it's not a big deal!" Spoiler alert..... it was a very big deal.
    via u/noodlemom72
  • 14
    lastone23 Didn't get insurance on a Polaris Razor. Side by side off roading vehicle. Had it less than 3 weeks and someone stole it from my driveway Christmas night.
    via u/lastone23
  • 15
    Had taken out a loan for 5 years.... Making the payment every month hurt knowing I didn't have it anymore. Only took it out once. 14k for the trailer and vehicle. Still hurts a decade later.
    via u/lastone23
  • 16
    [deleted] Wasting my time on my ex
    via u/[deleted]
  • 17

    It's never a sure thing, and sometimes it turns out like this

    Cjkgh Not selling $17k worth of this penny stock when it was hugely up over a dollar. I thought it would go more and it TANKED the next day
    via u/Cjkgh
  • 18
    zombieh Made a calculation error at work during my first few months there which led to the firm undercharging ~$130k on a project...how I wasn't fired/written up I'll never know
    via u/zombieh*****_
  • 19
    [deleted] My car was making a weird squealing noise. After a few days, it just did in the middle of an intersection. The timing belt snapped.
    via u/[deleted]
  • 20

    That's so crazy... firing doesn't even seem like enough of a punishment for causing millions in damages!

    Bobmanbob1 Not me thank God, but a new hire I fired his first day out of training for 3 safety violations. The last involved dropping a wrench from 100 feet up on a work platform onto the left OMS pod of Atlantis. 13 million in damages and inspection/launch countdown time lost. Xrays, borescopes, replaced the cracked tiles, etc.
    via u/Bobmanbob1
  • 21
    Cheezburger Image 10487077632
    via Curated Lifestyle For Unsplash+

    The image does not depict the actual subjects of the story. Subjects are models.

  • 22
    [deleted] Going to an expensive university for a degree I didn't end up wanting after all
    via u/[deleted]
  • 23
    Jeeping Trucker My ex. There was a very distinct moment when my instincts told me to walk away and I didn't, and now it's cost me the resulting 2 kids that came after that that I never see and endless child support.
    via u/Jeeping Trucker
  • 24
    suhryna At my old job, I forgot to turn back on the freezer after cleaning it (I got pulled mid clean to go do something else) so I didn't notice. Neither did my three managers. Over $10,000 in frozen product lost but that place was the worst place I've worked so f F Frozen Custard
    via u/suhryna
  • 25
    Fickle_Duck_4770 When I was a kid, my dad had a driver. One day, driver came to our house, saw little kid me and told me that my dad needed a watch for work and asked me to get one from his closet. I gave his driver a random watch and driver never came back. I gave the driver my dad's Patek.
    via u/Fickle_Duck_4770
  • 26
    [deleted] I transferred $500k to the wrong vendor. I practically had a heart attack, but the "wrong" vendor was another huge one so it was more like we paid an invoice a day early.
    via u/[deleted]
  • 27
    Also, my boss was more in a "everyone makes mistakes mood" and not her usual "I'll yell at you for 30 minutes. over a one penny error" mood.
    via u/[deleted]
  • 28
    P44 I had a small apartment in Munich and sold it for EUR 80,000. Now, it would easily be worth over EUR 300,000.
    via u/P44
  • 29
    ReplyIf YoureAnldiot My first car for college was supposed to be my stepdad's old project car: 1984 Buick Regal Limited. I put a lot of money in that car: new tires, rebuilding the engine so it can run again, new taillights, etc.
    via u/ReplyIf YoureAnldiot
  • 30
    Eventually, we came to the conclusion that it was just too much trouble to make it safe on the road just in time for me to start the semester. With all the money spent on it, I could've just gotten something that was drivable. I still love my Regal, but sadly she's still back home in the garage. :(
    via u/ReplyIf YoureAnldiot
  • 31
    ess Mach Service 928 OPEN brother Authorced Reseller NEW SELECTION OF CHAIRS ON SALE
    via TYLER4K on Unsplash+

    The image does not depict the actual subjects of the story. Subjects are models.

  • 32
    UnfortunatelyAva... Going to college. I went into mechanical engineering, because I like math and working with my hands. Turns out like 75% of it is learning to work with teams, which I hate and am terrible at. Now I have no motivation and have two years left that I am dreading.
    via u/UnfortunatelyAvacado
  • 33
    ace_cube Made a $30 phone call from a resort in Mexico, I was paying a bill through an automated system, there was no late fee for the bill had I just waited until I got back home!
    via u/ace_cube

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