What does a one-time donation between $10k and $100k do to help the second case? Perhaps it will allow the maintainer to take a few months off and work full-time on the project, or maybe hire someone to clear the backlog. But what happens afterward? Without a clear pathway to making the project self-sustaining, you've merely postponed maintainer burnout by a couple of years at best.

The biggest problem with occasional $15 donations is that they're occasional. Sustainability requires a somewhat stable ARR.