The secret is that if people pay you to do this thing you can't not do, you'll be able to do
more of it.
For instance: I can't not draw comics. I just finished spending four and a half years on a graphic novel. I like to draw them and I seem to be pretty decent at them if the reactions I've been getting are any guide.
But I have to pay rent. And power, and internet. And pay for my subscription to Adobe's Creative Suite, and upgrade my computer now and then.
If nobody's paying me to draw my comics, I'm going to need to find a way to pay those bills anyway. If I'm not lucky enough to have someone else pay them for me, then I need to get a job.
There are only so many hours in a day. A job will take up a lot of them. And I'll have to wedge tiny bits of making comics in the edges of what's left. I'll need to deal with a commute, and with spending all my energy at work, and just wanting to come home and sleep instead of draw.
So I draw my comics, put them out for free, and put a tip jar out with them. If enough people start throwing money in that tip jar on a regular basis, I can start cutting back on my day job. Eventually I can get to a point where I'm able to pay all my bills from comics, and don't need to worry about taking time from them to keep a roof over my head. I can spend my entire workday thinking about making my comics and drawing them, and get a lot more pages out a lot faster.
A lot of my fans are taking advantage of the fact that I'll draw comics anyway. But a subset of my fans have enough money to throw a few bucks my way and help ensure that I can make a lot more of the comics they like.
Does that make sense?