I have been seeing a lot of life-hacks about how pensioners move to south east Asia with their cash because the low cost of living and also to bulk buy properties and live on passive income.

You are going to have that problem with countries with questionable economic sovereignty (look at the Philippines in particular) instead of becoming a state with possibilities to do local development, you have oversea entities coming there to suck out the resources, labour, wealth and talent out of them and leave the place to die