Donations don't generate nearly as much money as purchases. I like open source just as much as the next person, but there's no way that I could afford to drop my job and go full time into an open source project. Looking at Lemmy's donations for example, the annual budget on OpenCollective is, at this time, ~$10k (which is significantly below US minimum wage at least), and their Patreon link shows $1650/mo. It's a nice chunk of cash, but not sustainable.

One approach I've really liked is what Aseprite does. You can buy the precompiled product, or you can clone the repository and build it yourself. Most users won't build it, so they get paid and still get to share the code with the community.