is correct. Any capital gain in another country is not taxable in Thailand until the proceeds from that sale are transferred into Thailand, and even then any tax already paid is a deduction against Thai tax, which for many countries might mean no tax is payable in Thailand
The most "mis-used" visa in Thailand is the non-O retirement visa. Over half of these are obtained through visa agents paying bribes to immigration because people can't meet the requirements. The DTV is most certainly an "upgrade" for retirees who don't want to spend the rest of their lives sitting in Thailand waiting to die! Many (like me) still want to travel, and the DTV is fantastic for this. It's a dream come true
Who gives a sh*t about the "real" target group. If you meet the criteria you meet the criteria. I don't see it as a"downgrade". Anything that avoids dealing with those pedantic immigration officers year after year is a bonus. There's thousands of retirees suddenly becoming "remote workers". It's so easy it's laughable