I don’t think Godot has a huge audience either. They are certainly no Unity nor Unreal.
The Patreon tiers are about what other people are willing to send your way, and another project has already given us the data points. And you might score that corporate sponsorship from a biggie like Microsoft which can (and should) afford it. Or a game company that is heavily invested.
Between the “$5 is high” and thumbs down on sponsorship, I feel like you’re being too shy. MonoGame has great potential, in part because it taps into the .NET/Visual Studio ecosystem, and a great story: significant MG games have shipped on all major platforms.
Be proud and provide the chance for people and companies to send cash your way.