The emphasis is on New Wealthy Individuals. I was in Central Embassy and the shoppers I saw there were Thai . A few other Asians. Thais with money will buy in Bangkok , but foreign wealthy will not., they have it all at home and in nearby countries. Also there a limit of stock they can have on hand, sizes , colors .
The foreign rich aren’t flocking to Bangkok. There’s nothing there for them. They’re used to California, Monaco, Cannes , Nice, Paris, where the hotel Palaces are and the world s famous chefs. Where they can dock their yachts and buy all the supplies locally. Or invest in wine country land houses like Clooney and Brad Pit, and have the fully qualified staff that they need to look after everything. Bangkok will never have that, could never give them what they need. Just the air pollution would frighten them away, no money can alter that.