Ask HN: Successful Non-Founders, was it worth it?

I've been asked if I would join a startup with as a non-founding, but critical hire. I've been offered a great amount of equity according to my research. I like the company a lot and think they're on to something. I can figure out most of the pros and cons of joining them, but don't have a sense of what it could be like assuming a really positive outcome. For those who ended up at really successful companies as non-founders, was it worth it? Were you happy with your equity when the company sold or had an IPO? Did the final outcome fall short of your expectations in any way?

Though the details are sparse, I used a throwaway to not upset the founders.