Depending on donations is almost always tenuous, especially if it's not anchored by big donors (and, often, even then).
There's even a school of thought that the existence of things like Patreon for funding open source development is actively harmful insofar as it can create the illusion that it's a viable funding mechanism for sustainable open source development when it really isn't.
As Vitalik and other people doing social-coordination research keep arguing - it's a matter of coordination and not of anybody being greedy. The feeling that your little donation means little is what keeps the whole swarm of users from donating.
There's even a school of thought that the existence of things like Patreon for funding open source development is actively harmful insofar as it can create the illusion that it's a viable funding mechanism for sustainable open source development when it really isn't.