I agree - Singapore is not cheap.
But as for expats in Asia making loads of money, well, certainly there are some, especially in “hardship” locations where they are compensated for a perceived lower quality of life, but Singapore is not really on this list anymore. There are so many young brit, aussie, indian, etc. professionals who want to live/work in Singapore now that supply is outstripping demand, meaning the old “expat package” is hard to come by. Not to mention so many Singaporeans now with similar or better international educations than the expats, and of course with better language and culture skills for the region. And remember that since locals often live with family and receive government subsidized housing (hdb), companies are used to paying less than what an expat would really need to have the same quality of life.