That might well be a cultural/geographical thing. Here people are more serious about the need for security. But then the pay is usually less in real terms. One of the things that continues to amaze me about the US is the number of people who clearly have the money to just get on and do something that they believe in (even when it doesn't pay). That seems (to me at least) much rarer in the UK and Europe. Is tenure in the US about security or status?

But yes, challenge and being valued are also crucial. The executors can be just as important (or more important) than the person with the ideas. Or am I just saying that because I realise there are lots of people out there with better ideas than me? :) (Actually ideas was never my problem - it was getting them to work but that's another story)