the chinese were the last phase of the mass tourism boom , I am sure thailand is not the only country seeing tourism downturns
though bangkok is top of the list for mastercard in sept 2018
The Bangkok international airport is the main arrival point for not only Thailand but the surrounding countries and people traveling on to other destinations using Thai airlines as well,so to count all arrivals as people having their holidays in Thailand is unrealistic
and now with the rise of the fascist govts in the west with their " fear johnny foreigner " rhetoric , I would guess most are staying within their own borders where they feel safer and do not have exchange rate issues