Have a cousin who had a great, old CJ for about a decade. He bought a bigger truck for work, got married and then ended up selling the CJ to a friend of his.
He told me he tried to buy it back from his friend a few years after he sold it to him, but they couldn't work out a deal. Goes without saying, but my cousin regrets selling his Jeep in the first place.
Regrets selling a YJ or TJ might be a different story for some, certainly. Still, I've had my YJ for 12 years and I could see buying another Jeep in addition to it, but I couldn't see selling it.