I live by rule "if everyone gave me 1 euro..." so I donate 1 euro/month to projects I use often (but I send actually 12/year to spare the devs some trx costs) and 1 euro/year to projects that I use sometimes (again I send 5 Eur/5 years actually). I use almost only open source and I haven't yet paid everyone. I also recently made an open source application where I didn't setup any donations channel, I simply like doing it.. Maybe in the future if I have more work on it, but not now..