Every single time I meet one of the developers of an open source project that has benefited me in some way, I always make it a point to tell them "Thank you" and let them know how (and how much) their generosity benefited me, and how much I really appreciate it. I also make efforts to help out in any ways I'm able. Sometimes that's cash (when I've got some available to spare), and sometimes it's just helping out in support channels, or bugreports / pull requests, etc.

Thank you for making the world a better place!

Not I, thank you. The folks who create and release open source software (which I myself have not done in many years now). I'm just reacting appropriately to their generosity which is actively contributing to the world being just that little bit better because of their actions / decision. :~)

Yes! Their generosity is an inspiration to me. Open source technology is empowering and world changing. I really admire these people.

You and me both. They're the people keeping alive the original "hacker spirit" from "ye olden days" of computers, back when it was all new and exciting to have an actual "home computer" on your desk at home. Almost all software back then was "open source" (though we didn't call it that yet). :P