alt Hacker News> they need to do something to get something, which is just how life is
FLOSS invalidates that statement.
Many people are happy to contribute to something greater than themselves. They also happily acknowledge they're standing on the shoulders of giants.
I'm not totally dismissive of FLOSS, but it's kind of a unique situation so you can't really extrapolate broad generalities about society from it.
Software basically has zero marginal cost, and is pretty unique in that regard. If baking 1 loaf of bread was identical to baking 10,000,000 loafs, we would have solved hunger centuries ago...
There also is the fact that a large amount of FLOSS is an exercise in resume building (FLOSS contributions is SWE resume building 101), and one rung lower, an exercise in ego building ("my design runs on millions of computers daily" is definitely something a human would value). So I wouldn't call it completely selfless (we are now also at the boundary of the philosophy of "selfless acts").
But in short, there is a reason software is pretty much the only field with a vibrant "free/open source" scene. It falls off a cliff once more than pressing keys on a keyboard a few hours a week/month is involved.