Was it intentional or unintentional that your comment also describes the life of entrepreneurs/startup founders?
And if an entrepreneur is regularly pulling all-nighters for no good reason, he is probably doing it wrong. Sleep is worth its weight in gold, and you don't give it up for anything less.
I imagine most of us do it because we think it's for a good reason.
IPOs? You shouldn't need an underwriter to do an IPO. That's the whole idea behind OpenIPO -- which is how Google itself went public. It's true that the investment banks have access to a larger pool of investors. But that's circular reasoning. If the investment banks didn't exist, then these capitalists would be investing in IPOs through a Dutch auction like OpenIPO.
Structured products? The investment banks earn a 50% profit margin on structured products. The people who buy structured products could double their returns by constructing their own structured products on the options and future markets. And if they're not sophisticated enough to do that without an investment bank, then they probably don't understand what they're buying!
In my corporate finance class they described how some countries (I forget which) had experimented with auctions instead of using i-bank underwriting, and in the end they had all gone back to using i-banks.
I don't know anything about M&A, but on structured products I agree they are just for customers who don't know any better.
I have a good friend who is a COO a very successful start-up. He said "When we IPO you better believe we're getting Goldman to do it".
It's a free market, no one HAS to use these IB firms and take a 10% haircut on the money they raise. However, they choose to do it.