Sales of anti-Elon Musk bumper stickers for Tesla owners are booming.Matthew Hiller, the creator of the viral "I Bought This Before We Knew Elon Was Crazy" sticker, has seen record-high sales.The sales spiked after Elon Musk's appearance at a Trump rally and following the election.Other EV makers like Ford, Rivian, and General Motors could benefit if Tesla buyers defect on a large scale.