Just because people make profit does not mean profit is their "only" goal. And like Paul Graham explained in his Y-combinator speech, there are certain services to humanity that simply would not work if they didn't make profit.
I think it's ridiculous to say that people like Steve Jobs are in it for profit. If Steve Jobs was after profit he would have been a highly successful wall street CEO or something. He does what he does out of personal ambition to improve the world. It's the same for 37signals and I would argue it's the same for Y-Combinator.
Well that, yes, and a bit of vanity I am sure.
37signals is really good at making you realize how these web companies might not be the best business to get into. Could there be a bubble slowing building that will eventually burst?
The unique part is 37Signals seems to concentrate mainly on PR. They're not the biggest or best, they just shout the loudest.