Patreon only takes a 5% cut.
They make it look like the extra 3% is to build features for their platform, but the VC funding is for that, and other than developing the feature, having tiers doesn't cost them anything. Charging 8% just makes it a bit closer to being sustainable.
Isn't it only unsustainable for VCs who want 10e50% growth ever three days?
For a $1 payment, they actually take 20% (10c + 5% + 5%).