I don't know any expat that have all their investments in HK and I know many that have none. Most have something back in their home country and most people I know that buy stocks have some here and in the US and/or home market.
Now your scenario of course is theoretically possible but I consider it unlikely.
In any case, whatever one decides to do with money, there's always a risk. If you keep it under your mattress, it could get stolen, if you put it in the bank, it could go belly up or a currency can fall dramatically coupled with inflation and all of a sudden you are much poorer than before. Many countries have experienced that situation(Indonesia, Mexico and Argentina just to name three)
Personally, I milk it when I can because I know there will always be darker days and that doesn't preclude sitting on the beach and relaxing(not drinking for me, I hate alcohol), quite the contrary in fact. I'm mostly traveling these days and I can thank my investments for it...Freedom 45 baby