[gshdg]

I think there's a third set, which is people who like seeing other people use the stuff they built, whether or not it makes money.

[ChuckMcM]

I totally agree with this too. So three sources of joy; money, elegance, and utility. Of course that reminds me there is the "other" side of developers the ones who find joy in puzzle solving, overcoming artificially imposed barriers, and discovering protected knowledge.