According to Thailand's official rules, you can bring up to $20,000 USD or the currency equivalent into the country before you have to declare it to customs. If you're bringing Thai baht (THB) into the country rather than a foreign currency, the most you can carry with you is 500,000 THB.
The Thai banking system is the wild Wild West where no one really says anything about where your money comes from
Maybe you wake up on a random day and say you know what I want to go to the casino in Macau/dimsum in HK/skiing in Japan/expo in Singapore/shopping trip in Dubai/etc etc etc …
when you return from your international trip you have to once again fo to immigration for your “first” 90 day report
Yes I said “first” because in essence it’s your first one since you returned to Thailand