You would be surprised how liveable some places in Southeast Asia can be. I think most of the hate/disgust comes from cultural shock, not from the places truly being unlivable shitholes.
You mentioned only two places -
Thailand and Vietnam.
Vietnam is not the best place in SEA, I agree. Major cities are overpopulated, the northern people behave like the Chinese (I mean that in a negative way). I've read some statistics that 75 % of tourists would come to Thailand again. For VIetnam it was only 5 %.
In Thailand, there are many retirees,
digital nomads, expats, passport bros, how ever you want to call them. Many of them very wealthy (they may not appear in these statistics at all). And most of them seem pretty happy. Thailand (mixed with neighbouring countries) has some of the best food in the world, if you eat street food from strange sources you may get diarrhea yeah. And for $5M you can buy not just one villa but a dozen of them outside of Bangkok. The locals are very honest and polite with a few obvious exceptions like taxi drivers.
Then you have dozens of other countries friendly towards
rich people willing to move in. The statistics and the map from VisualCapitalist you showed us tells only one side of the picture - rich Chinese and Indians were getting residencies/
investments in US, Canada and Australia. That is nothing new and not surprising if each if these countries (CN, IN) has over a billion people. The number will be high. Not surprising. The only surprising number for me is
Greece getting 1200 net new millionares (not sure what that is about)
However, all this is backwards looking. You should be looking one or two steps ahead - where is Canada heading with all the new Indian immigrants and woke politics? Where is Australia heading with the new regulations and controls? Where is UAE heading with its new tax? There are not the countries you want to be in for the next decades. You should look elsewhere and some countries you may call "shithole" may actually be perfect, for business opportunities, dating, lifestyle, weather or simply the government leaving you alone.