what? people with private planes are the ones running leaded currently. people who aren't very wealthy are flying on commercial planes that haven't used leaded gas for decades.
Wealthy individuals’ airplanes are already burning Jet-A in turbine engines.
Who’s piloting the airliners that the not very wealthy are flying on? Working pilots.
In what type of airplane did they train? Piston engine aircraft.
Now that they need to have 1500 hours experience before taking the yoke of a commercial airliner in the US, where will they get that time? Overwhelmingly in piston-engine aircraft. Typically as a flight instructor, which will go to near zero if you kill the ability of practical intermediate distance travel to be done by high-compression and/or turbocharged light aircraft.
(Alaska and Caribbean islands also has a lot of very much not rich people flying around in or getting necessary supplies delivered by 100 octane needing airplanes.)
Commercial operations using 100LL dwarf personal plane operations using 100LL. Cape Air burns way more avgas on a Tuesday in July than I burn in a year.
Back to “Very wealthy” individuals running turbines. If I could afford it, I would be too. It’s a better engine solution (almost) all around, except the operating costs are a low single-digit multiple higher and capital costs around 10x, which puts it out of reach of almost every individual. No one should cry for me here, but there’s a huge subset of 100LL-based operations that you probably approve of or judge essential and want to continue.