I do it for the passion. I'm curious and I think knowledge is the only thing that can really push the mankind to something better. Yet, as my PhD studentship is getting older and older (and I hope I will definitelly finish this year!) I'm realising that I may be forced to leave it someday for some better paid job. It's not about big money, it's about living normal modest life, not needing to worry if I have to buy a discount food, to have some money for my hobbies, for once-a-year vacation, for raising a future child. Still I'm not ready yet to leave this world of wonders and sights.
When looking for other options I'm thinking about maybe some company application support, helping to solve problems of others. I like to analyze and find the solution. It wouldn't be science though, but I would feel like I'm helping it in an indirect way.