Why do private jets even exist. Why can’t people use first class on planes? Or helicopters?

Or high speed trains. Oh wait, Americans have no clue what high speed trains are or even heard of them.

You can't see how Taylor Swift on an airplane wouldn't be chaos?

Because flying commercial sucks and the costs of owning and operating a private jet are basically zero after the numerous tax benefits are taken into account. It's the difference between a limo and a luxury section on a train.