Donations to free software projects are pretty important. Since most of big ones are maintained by companies which has a partnership with foundations, lot of most free software projects (libraries, components, apps, etc) are maintained by small amount of volunteers, who paid everything for the project.
So, this not mean to make you rich, but at least having a coffee paid by some Lemmy user who uses your piece of software and wants to be grateful, makes you a bit more happy.