If you have it, why worry? It's only a problem if you can't afford it. And of course it depends on what pre existing conditions. Probably everyone over 70 has pre existing conditions, and millions of them are insured.
the trouble is flood of drug money fuelled Chinese buyers means everyone loses out. In London, we let anyone buy anything, now the Russians own masses and prices for Londoners, are sky high. We all lose out because Thailand wants the foreigners cash but not the foreigners. Every scheme will be abused in a country where 'under the table' buys anything.