It depends. A common scenario in finance here is that you end up maintaining a specific piece of legacy software, often using ancient or unfashionable technology, and it can be
very hard to sell yourself to another employer as your useful-to-anyone-else skills erode. Your bosses know this.
There are various tech roles in hedge funds and in finance, and it sounds like the @throwaway___ is in a role that is considered "IT" rather than part of a quant/trading desk, which translates to no real bonus, and to not being considered a source of revenue.
This isn't Silicon Valley. Rightly or wrongly, they just want someone to come in at 9am, work through their assigned bugs and feature requests, get a sandwich at Pret A Manger at 1pm, work through some tickets and go home at 5pm. Nobody's interested in hiring "hackers", experimenting with funky languages, or doing anything remotely unpredictable. If you're on a trading desk it's a different story, but it's definitely possible to work at a hedge fund or an investment bank and get a shit deal.
Edit: Basically, it's your responsibility to maintain your skill set, by any means necessary. Your employers aren't paying you to be a well rounded developer, even if you think they should be.