Because FB is full of nasty people. Ignore them, they ar sad individuals. Never take any insults you get on social media personally🙏
Unfortunately, I cannot help you as I am just starting to look into Thailand. It might be best to call their embassy directly to find out about the different visa requirements. And as people mentioned before, it depends on the country you are entering from and the kind of passport you hold.
As of expenses, Thailand is, compared to most western countries, quite cheap.