I used to work in the industry. My understanding is that the vast majority of private jets (not including general aviation) is owned by or managed by firms that charter out their jet. (Like a taxi business). Of course there's nuance between those business models.
Yes kind of, but the leasing companies have only one customer, see
"Lewis Hamilton avoided taxes on £16.5m jet using Isle of Man scheme
The big four accountancy firm EY and Appleby [..] helped Hamilton and dozens of other clients set up seemingly artificial leasing businesses through which they rented their own jets from themselves."
