>>Working for a cool startup is very very cool.

No, working for something like Google or Facebook in its start up days is cool. And that is like once in a 15 year opportunity.

In reality you can do a lot of things on the side in a 9-5 job. Than working crazy hours at a crappy start up .

Yes working at big companies is not very much profitable, but neither is working at a bad start up. Bad starts up are worse than big companies.