Three reasons:
1. Higher Patreon numbers display how important a Social Justice Warrior is. It's practically a life gauge for them. This is why a great many of them (Randwhale for instance) artificially inflate their Patreon numbers. The amount in their Patreon gives a clear indication of how strong their cult of personality is, and concurrently how much their insight is worth to followers. The bigger the Patreon budget, the bigger the fanbase backing them, so the more likely they are to get speaking engagements and the like, which means - you guessed it - more victimbux from speaking engagements.
2. Brianna's Patreon is her "fucking around" fund. Most of the Wu family's finances are managed competently, giving Brianna Wu enough money to live comfortably, but Wu has a bigger love of flash-in-the-pan than Chris himself does, and Patreon lets her indulge that. She's made over $35,000 from her Patreon alone counting her inexplicable $10,000 gift from Cliff Bleszinski, and though Wu claims to pay Natalie O'Brien using this money, the fact is it goes mostly into letting Wu buy expensive toys and enabling her to feel important. You'd be amazed how much easier it is to book a speaking engagement when you can easily grease a few wheels.
3. Wu's justification for her Patreon is twofold: A burgeoning legal fund for
the mission statement she outlined during the Derek Smart incident, which revealed that her knowledge of both the legal system and civil rights is
hilarious, and
the primary means by which she pays Natalie O'Brien. The lower the Patreon goes, the more the illusion fades that there is anything remotely genuine involved in Wu's claims but smoke, mirrors, and hilarious failure.
