The big difference between this and all of Musk's other ventures, is that this is performing a wheel change whilst you're still driving the car. Everything in Tesla and SpaceX has been more or less built from scratch, and involves the release of new products, which can slip. If Twitter's servers fall over, or some Nazis manage to co-ordinate assinating Nancy Pelosi whilst he's at the wheel, or he accidentally endorses an anti-free speech authoritarian regime that hack up journalists with bonesaws... he's going to be in trouble. Because anyone with any sense will leave, and network effects go both ways.