That's not entirely true. It's about how you enter the country.Doing it on multiple visa exempts and extensions incl border runs,will eventually get you flagged by immigration way before 180 days. The 180 days limit is tax related.
You can extend the stay year after year.If you want to leave for some reason, you just get a single (฿1,000) or multi re-entry (฿3,800) permit at immigration or at the airport. Dead easy. Then you must return before the 1 year extension expires. Otherwise you need to start all over again.
Start with a 90 days Non-O based on retirement,open a bank account in Thailand,deposit 800k baht and then extend the stay 1 year at the local immigration office.You can then do this annually for 1,900 baht/year. Imo stands for in my opinion. You can always get a health insurance when you're in Thailand. No need for a mandatory one.
You can open a bank account on a 90 days Non-O based on retirement and from there extend the stay for another year as long as you meet the financial requirements. This is by far the most popular method for retirees.