Walk up to the falafel stand and hand the guy $3. He hands you a falafel, no onions.
This for that.
Something for something.
The time between surrendering the money and getting the sandwich is tiny. You gave him something, you got something. It's simple.
Now, stretch it out a bit. You order dinner in a restaurant. They treat you nicely, the room is beautiful, you enjoy the evening, then you pay the bill. This, pause, pause, pause, that.
Go to law school. Pay a lot of money. Spend a lot of time. Be taught a bunch of things you don't particularly want to know, things you probably don't need. Get a degree with a modicum of scarcity. Pay for a bar review course. Pass the bar. Then you get a job that pays a lot of money.
This, then a multi-year pause, then, in return, that for the next forty years. We call it return on investment.
Online, though, I'm not sure the math is so obvious. You don't write a blog to get gigs. You don't help people out in a forum to build a freelance business. Sure, that might happen, but that's not why you do it. If you are busy calculating quid pro quo, that means your heart isn't in it, and the math won't work out anyway.
Online, the something, the quid, the this, doesn't cost cash. It takes heart and energy and caring, which are scarce but renewable resources. As a result, many people are able to spend them without seeking anything external in return. Even better, the act of generosity, of giving without expectation, makes it easier to do art, to create work that matters on its own.
I think it's more like Santa math. Santa flies around the world, giving stuff away, and for what? He earns gratitude, trust and friendship, that's what. Sure, one day he might decide to license his image or try to sell you something. But right here, right now, gratitude, trust and friendship are plenty. Especially if you enjoy doing what you're doing. Quid, no quo.