cannot speak about mistake, when thailand has much higher gdp per capita than adjacent countries and multiples of their tourists.
thailand grew it's economy without much effort by torism in contrast to china and others, who had to work. so they reap a lot and did well. just watch the lavish lifestyle of many thais, and how many porsche, bmw, mercedes and teslas are driving around. poor people are mainly from laos, cambodia, myanamr who work here. however most thais are well off, probably close or better than many european countries already.
few years ago, thailand was only known for prostitution. nowadays many mfamilies come and thailand is number one destination that ppl talk about in europe. they attract many "quality tourists" already