Avgas utilizing planes are not simply rich people's play thing. The vast majority of hours flown in these planes are for commercial, money making purposes. They are operated by real businesses that earn profits and should be able to afford the transition to non leaded gas.

> Public safety agencies, however, which account for one-quarter of piston-engine planes registered with the Federal Aviation Administration, are “likely to consume more than half of all the avgas used by the fleet,” according to the January National Academy of Sciences report. These agencies often include law enforcement and firefighting aircraft that need to reliably stay aloft through rapid changes in temperature, pressure and altitude. Personal and recreational flyers make up the remaining three-quarters of planes and consume the other half of leaded gas.

https://www.nbcnews.com/business/business-news/leaded-gas-wa...

So roughly 50% of the leaded fuel is used in personal/leisure flights in the US. I wouldn't consider the other 50% anywhere close to "the vast majority", and from the source, and it's largely safety and rescue.

Moreover, demand is expexted to grow precisely because of leisure and high net-worth personal use[0].

Now, unless you include business trips of rich people as "money making business", there are very few commercial fights otherwise, serving mostly remote, low demand areas.

[0] https://finance.yahoo.com/news/aviation-gasoline-avgas-marke...