I was the first employee at Twitch, back in 2007. It worked out very well for me, but - having watched the sausage get made - I'm very aware of how incredibly lucky I've been. It could very easily have all come to nothing.

To be honest it's not something I'd ever advise someone to do, even though it did happen to work out for me. I'd advise most people to join one of the big giants and enjoy a predictably comfortable life, and those with a certain temperament - like myself - to found a company instead of joining one.