Earlier quoted context omitted.
Recognizing it's merely an example, I think nonetheless it would be good to present examples that are actually compelling. Let's think about your example and what it entails. So you're going to a pizza party with your friends, and instead of saying to your buddy Mike who you're about to see in person and share some pizza with, "Hey Mike, here's 5 bucks, thanks!" Instead you fire up the ol' ethereum whizbang machine,…
You could make a similarly incredulous argument that messenger apps are totally ridiculous because why would you use a 500 dollar handheld computer to write a message through the "internet" when you could just talk IRL? I mean, like, within three years you'll probably be having a virtual reality pizza party with your friends on the other side of the world. That's less wasteful of resources than flying, you know! And…
How is it better than existing methods for doing whatever you envision doing with it?
What if anything, does it enable that would otherwise be impossible?
So you've got nothing?
"Ha-ha! Why would I use PayPal when these smart contract blockchains technologies have been working well for many years?"
So instead you go to one of the future's several competing smart contract platforms
Simply positing a future scenario is not an argument for it's likelihood.
Why do I need a massively parallel system with enough energy to power a city to do this when I could just do it manually, or write a script to do it and run it locally? If one of the donators doesn't trust me or my code, then they can just donate to wherever directly.
I don't even get your scenario, what value is there in me/my contract being an intermediary between my fans and these other organizations? (and isn't GitHub a for profit company? Why would you donate money to them?)