Off topic a little bit as you mentioned it.
Perhaps your doctor is like my doctor and understands that a PSA check is not a good way to detect prostate cancer. It’s nothing more than a possible indicator. A high PSA doesn’t mean you have prostate cancer and a low PSA doesn’t mean you haven’t got it. That’s possibly why your doctor is not advising you to get it. Unless you have other symptoms it is not advisable as a routine check and far more useful for checking progress of the cancer once it has been confirmed. If you are concerned or there is a history working your family you are far better getting an MRI scan. Even that though requires a qualified specialist to interpret the scan correctly.
I take your point about advanced bookings, which would normally be the case. However, with so much uncertainty for rules at home and for travel, I think many people won’t have decided what or where to go in December and January. If Thailand got their act together, they could still get a reasonable share of winter travel.
If there is a rise in cases in Thailand it would have little to do directly with foreigners and more to do with Thais going on holiday and Thais mixing while working in restaurants, bars and hotels. I’ve no doubt Thais will blame foreigners, as they are brainwashed to believe nothing bad originates in Thailand and foreigners are the cause of all their problems.