It pains me to say it, but self-promotion is a necessary thing sometimes. We would never get where we wanted to be if we weren't our own biggest cheerleader every so often. At the same time, it is a skill to do it in a way that is not a. nakedly self-serving and b. cringe.
You know who cheerfully disregards this knowledge and showboats it all over the internet to the horror of the rest of us? Pretty much anyone who has a career that involves bragging on LinkedIn and Elon Musk's Twitter while making a lot of money (or wants to).
Few do this better than venture capitalists, i.e. the people who invest in the people who bring us much of the cringey grindset influencing, yet somehow manage to be even worse. It's fair to say that it's a calling that attracts a few big egos, as we can see in the examples below.