To me, money was always the least consideration. The content of the work, how much I'd learn, the atmosphere and co-workers, open source or not, that was generally what made me pick one job over another. Often when I had several offers, I ended up picking the lowest.
And yet, when I've worked there for two years and learned a lot and did some good things there, and I still haven't gotten a raise, I don't feel appreciated. And when I don't feel appreciated, I look for something else.
In my experience, I've found that the times I want more money falls into a few categories:
1) Cost of Living
- This can change bc of higher rent, getting married, having a kid or a million other things
2) I'm unhappy about something else
- When I have another issue with my work, it often leads to what many people have said in other comments..."I'm not paid enough for this" which can take many different forms. Addressing this is much more important than whatever financial increase you do or do not get in asking for it.
3) Envy
- If you find out all your peers at similar stage companies are paid more than you, or that your coworkers are, you'll probably want a raise.
In my experience, #2 is actually the most common that leads you leave and even if you get the raise, a manager needs to make sure they treat the condition (whatever is bothering you) not just the symptom (I want more compensation for my work).
And yet, when I've worked there for two years and learned a lot and did some good things there, and I still haven't gotten a raise, I don't feel appreciated. And when I don't feel appreciated, I look for something else.