wow you're not kidding! looked this up and revenues are somewhere like 10x-20x of macau compared to vegas. That's pretty nuts, didn't realize there was that big of a gap
Like, if you like on the American east coast, and enjoy gambling, Vegas may be a place that you'd like to go, but you have other closer options.
Macao has not only China but is a quick flight for most of the world's population, particularly NE and SE Asia, and most importantly most people are not residents of Macao. In East Asia, where gambling is allowed it's usually not permitted for the residents of the country (e.g. Singapore)
singaporeans are definitely not "not permitted" to gamble.
i suspect you mean the thing with the casinos. singaporeans can enter, though they have to pay an extra fee. and besides the casinos, singaporeans also bet on 4d, toto and football in betting shops all over the island.