So then I wouldn't say it's a dumb thing to do. He has a prescription. The law says you can bring in 30 days worth of medication, he wants to bring in 90 days worth. It's just like the 1L of alcohol. If you bring more in, you can either pay a tax on the excess or they confiscate it, really not a big deal.
The purpose of the laws regarding the maximum quantity of medication you can bring is, is to prevent/restrict people from bringing in stuff to resell here. If you have a legitimate need for the medicine and for a 3 month supply you won't have any issues.
If you're 18 years old and bringing in 5 years worth of medication, you'd probably have to spend some time there.
Alright, I understand what you're saying. The requirements for the retirement visa are there so Thailand knows you'll be able to support yourself if you're here for a year. You can either have 800k baht in a Thai bank account as proof of savings, or have an income of 65k baht, or a combination of the to. It's not ideal, but that's how they do things here.
If you have 800k baht equivalent in your UK account, the only other option would be to fly back to the UK an apply for a 1 year Non-OA, the money doesn't need to be brought into Thailand BUT this visa does require specific Thai health insurance.