Unless you've worked for an investment bank you have no idea how much money they have. It's like a giant gulf-of-mexico-style money gusher that doesn't quit.
How do they make it? CSFB flies on the bleeding edge of what's legal and always have. I was there when Frank Quattrone was involved in the IPO of VA Linux. The share allocation resulted in the US vs Quattrone lawsuit. Imagine you facilitate an IPO and you get to hand out shares at $80 a piece to your buddies on and the first day it pops up to $300/share and you can sell - right then. http://bit.ly/cBMdqb
I was also there when James Archer, Jeffrey Archer's son was found guilty of manipulating the swedish stock exchange and banned for life. http://news.bbc.co.uk/2/hi/business/1459638.stm
In investment banks there is what's known as the Chinese Wall. It separates investment banking from the brokerage divisions to prevent conflicts of interest. Imagine you have a bunch of guys buying and selling stock for the bank's account and another group of guys recommending to customers which stock to buy and sell. They're all in the same building, using the same elevators, the same mens rooms and the same lunch hall. Quick entrepreneurial quiz: Anyone see a business model there?
They take their licks though. I was there when the LTCM fund collapsed and they lost $600M. Also when the Russian economy collapsed and they lost another $600M. Layoffs? Nah - business as usual.
If you're a developer or ops guy and get tired of startups, I strongly recommend going to work for an investment bank. It's very very hard to get your first job - you're going to have to network your ass off or have a seriously hot resume - probably both. But once you're in, provided you're good at what you do, it's very easy to move between banks and promote yourself into better jobs in other banks or divisions.
So what the fk am I doing running a startup? Good question. I ask myself that sometimes. When you look at the opportunity cost from the "I could be in an investment bank" perspective it is scary. I don't have some magic answer or a bunch of bullet points. I guess what draws me to it is the fact that I own my own business. It's also completely honest. Your success is your own and so is your failure. Working in banking feels like cheating. Perhaps it is. But it pays cash and lots of it.