@Michael *******
it's possible to extend this visa while in Thailand, you'll need to again show 500k. We don't know yet. Or, you'll need to leave the country and come back
At a minimum, with the DTV, you'll need to leave the country every year. That will eat into any profit you make by having money earn interest.
Plus, the non O for retirement doesn't require you keep any money in the bank. You can meet the requirements by bringing in 65k/month, or for some folks, showing documents that you earn that much.
IMO, DTV makes sense if you regularly travel out of Thailand. If you don't, non immi O for retirement purposes might be better.