Until recently, renting a yacht in Thailand was incredibly expensive due to the import tax imposed on yachts, even if they were used for charter tourism. A few years ago, the rules changed and the purchase costs of charter yachts fell sharply. The prices are now in line with the international standards.
Search for your boat
If you like to sail in a well-organized environment, then the Caribbean or even the Seychelles are a better option. However, if you are in for an adventure, then Thailand is for you.
It is one of the destinations that we know through our work, of which we wonder why no more people make the leap before it's too late. Some experience with anchoring and different weather conditions is recommended in this area.