insurance + hotel is what's expensive or extra cost yes, rest is same like flights, but if you're staying for a longer time, since Thailand is cheaper than like Europe, can be worth it
If you are willing to quaratnine for 15 nights at your own cost are you still willing too? Although it's amazing, quite empty, maybe even a bit cheaper now in my experience and covid free(very few cases) once youre free
my bf been 5 months in Thailand apart, I know exactly what you mean, going back now next week though, then when I'm freed from the quarantine, it will be almost 6 months (minus a week)