I knew people like that. First of all, the first few years are a grinding machine and it pays shit (relatively speaking). You spend literally all your waking hours at the bank, w-e included and even when you have some time off, the bank restrict what type of activities you are allowed to do. Every year, the bank unceremoniously fired the bulk of your team. Anything is fair game to get the upper hand. There is no such thing as a friend. Even if you are in a team, there is no such thing as team work or team mate.

If you survive 4 years, then you get into the really well paid positions with 300K bonus a year being common. I have seen 2 scenario unfold: either the 4 previous completely ruin your value system, so you are either a complete asshole or addicted to a life of excess that keeps you in the system. A few will get promoted to hire levels yet and enter a weird world of mostly networking.

In rare circumstances, generally the one lucky to have a good and sane social circle before going into the grinder, you retire at 30 with several millions in your bank account.