Let's stop here, I don't get the impression you know anyone whom you are talking about. More likely you watched a rerun of Wolf on Wallstreet.
Hope you know dot com bubble #1, LTCM, housing crisis, Lehman, Bear Sterns, Kidder Peabody, Traveler Group, First Boston etc. Wall Street is always fluid. Almost no one stays at the same firm, same group, or doing the same over 15 years, or 10 years. Wall Street firms are like revolving doors. Hundreds of hedge funds shut doors each year. I get friends who made fortune in their late 30s. They quit regular jobs, found some wives and bought farms in CT, NJ etc. Then they trade their own money. Why do they care about the track record?
So you want to say they are Wall Street wash-outs? Sure you can if you want.
They are certainly some Wall Street people in their 50s and 60s. I do not want to make comments on them. I can only say that they love their jobs. They are jobs. Some need the $$ and some just love to work and feel important.