Yes Thai Bank rates are low. I do have all my accounts with Bangkok Bank of Thailand because all the transfer fees and poor exchange rates it actually is better.
You can live a good life if you have at least 2,000,000 Baht that you can keep for emergencies only and 50,000 Baht per month. // If you want an active nightlife then you will need more.
I am 85 and still in good health. I know at any time I may need personal care. I hired a very nice woman 60 YO to watch over me and care for the house. She needed help and I truly appreciate her being here. She lives in my house. I give her 25,000 Baht each month and she does the shopping for the food and what we need and she pays for it She takes care of the house and does the cooking. She does not complain about Money so she must have enough left for herself. What others do I have no idea, I know I have a friend and do not live alone. I can afford to have her here and that makes life much better.
What kind of nonsense are you doing. Put the B,800,000 in an account and leave it there. If you can't do that then leave Thailand. I have received 27 extensions and always have to show the bankbook and it has to be up to date on the day of applying for an extension. The B,800,000 has stayed in the bank all those years. I have other accounts for a living.