totally incorrect. You're a resident if Thailand is your place of living. No matter the visa or how many days you stay there. This is also the interpretation of European banks.
already many countries banned crypto and even more will do it in the future. You can't buy anything by Bitcoin, you need to exchange it into fiat currency. And then the government can ask you: where do you have it from? :) sorry, Bitcoin is not a solution.
It's not only about Thailand, but more or less about the whole world. I have no proof, but I suppose Trump ordered (maybe through OECD or the global bank?) that banks have to be more serious about non residents. I suppose it's about hardening sanctions on Russia. It looks like the only place for - somehow - safe banking is your home country. A bank account anywhere else - even with a solid foundation - can get blocked (short term or long term).