To be honest any sensible person travels with an insurance policy. I've had an annual policy that covers both me and my partner for many years. It covers us in the event of actual covid sickness, as any decent policy would, and up to a limit much in excess of that required by Thai policy. Therefore there is no need to take out an additional policy. If your travel policy doesn't already cover this you are on the wrong policy and may just have gone thoughtlessly for the cheapest option. You get what you pay for!
All you whiners about this issue should be looking in the mirror. There is nothing wrong in a third world country requiring people to have health cover to protect their public hospitals from unpaid for treatment for visitors. There is no analogy with guests leaving a restaurant with their bill unpaid. The protection is needed against visitors having weeks or months of treatment and then dying with their bills unpaid.
There are many things wrong with Thailand, but trying to protect their own public health service for the benefit of their own poorer population isn't one of them. And their poorer population are much poorer than those visitors being asked to ensure that their own costs are covered.
Even in the UK(nominally a First World Country) the NHS is not generally free for tourists.
Just for Bluskytoday please find(again) a list of countries, many of them "first world" countries that require proof of travel insurance from tourists.
https://www.insuremytrip.com/travel-...vel-insurance/