Would you leave a stable corporate job to be first employee of a small company?

There is a shit load to do so you'll be working 60 hours a week, you take a significant paycut cause the company is living on seed or series a money, and you most likely don't get equity. You'll get what, 1% in stock options at the most (probably more around 0.5). It will take several years to vest (again, the average tenure today being around 3 years you won't see all your options vested), most likely will be deluted in series b.

And the funny thing is that they'll start hiring a few months after you, and the budget approved by the board will be higher so other employees will make more than you.