Not to offend anybody, but this isn’t exactly a very high bar for “wealthy.” If you have a net worth of around $2 million (including a house in your home country) you could make it work pretty easily. At half that or less you are taking some risks, but it still isn’t out of reach.
While I wouldn’t choose Thailand right now, I wouldn’t have had a problem with it two years ago. Maybe when things are a little more “normal” I would contemplate it again. The big things that make Thailand a hard sell are when the quality of life equation gets inverted— feeling like you are a walking ATM, being hassled, no smiles, things being dirty when you expect them to be spotless (last one isn’t intended to describe the streets or klongs of Bangkok).
If you have an income stream of $80k/year, your money is going to go a hell of a lot farther than it might in the US, UK, Europe. If you are making $120k you can live quite well.
….now, if you start talking about the “super rich” that have ~10-100x the assets, the equation might not tilt in Thailand’s favor as a full-time residence. But, those people have multiple homes, and the novelty of having one in Thailand might make it worthwhile.