I'm sure people have done it, but they would have to lie on their application. The application asks which country you currently are in and Thailand is not an option. They would have to say that they are not in Thailand, risking rejection (not sure if there would be any other consequences).
Anonymous participant financial evidence of no less than 500k means show that you have 500k. I follow various visa groups pretty closely and I haven't seen anyone receive a DTV without proving that they currently have at least 500k in their bank account. When I applied, I provided a brokerage statement showing more than 500k, but they didn't accept it. They said I needed to show the money in a chequing or savings account.
Anonymous participant not sure how payslips can prove that you currently have 500k liquid. Seems that would only show that you've received that amount from your employer, but not actually saved that much. I can see how that graphic is a bit confusing though.
You have to show that you currently have the equivalent of 500k baht in your bank account. Each embassy/consulate has different requirements for how many months of bank statements must be shown. It ranges from 1-6 months.
don't actually have to leave for 5 days. No restriction on the calendar year, just 180 days per entry (plus 1 extension per entry if wanted), unlimited entries over the 5 year validity.