@Lê *********
No it’s proof of funds - 20,000 baht cash or equivalent in a major currency. Cash only. Bank statements or a credit card or phone app won’t suffice.
Then accommodation booked for at least the first few days.
And then a ticket out of Thailand within the 30 days. Can be air or bus, but if the latter has to be an international ticket out. A ticket to a border town where you could walk across the border doesn’t cut it.