I have had a Bangkok Bank acct since 2017 and send money to cover my rent and electricity for a studio I rent by the year but only come to CM as a tourist now.
Does this affect me if you know? I am not in Thailand now but will be visiting soon.
I have never needed one from Thailand coming or going, but in Singapore two years ago, I was forced to buy a return ticket to Singapore.  The attendant at the airport claimed that was a rule.
I chose a cheap SCOOT ticket and after landing in Thailand canceled that return ticket.