There's a somewhat famous quote from Samuel Johnson:
No man but a blockhead wrote but for money.
And there is doubtless some truth to that. Still, there's the obvious retort which I've yet to hear made to it: No man but a blockhead ever got out of bed.
Very few people would do anything if they weren't a bit foolish, in the sort of practical way that this quote implies.
(Incidentally, since I haven't seen the original, I'm inclined to suspend judgement on what it actually means; Johnson was too well respected by too many authors that I respect for this quote to be likely to mean little, or something very crass.)