I think both Las Vegas and Macau have a big fan of gambling, but we don't know for sure how big the fan. Both Las Vegas and Macau makes a lot of money from gambling, and that makes two places will be a heaven for the gamblers. But still, there is no valid info or data that will show the biggest places that gamble the most because the data or info will always change. Maybe in the next year, that list can change as the government gives the casino a chance to reopen their business.
Las Vegas is awesome, it's always such a great trip and vacation. I haven't been to Macau yet but I want to check it out after all the corona madness is over. In terms of online casinos the data might change easily, because people can switch around to other casinos very quickly. But seeing new cities such as Las Vegas or Macau is not very realistic I believe, because it takes a huge infrastructure to support such a gambling environment. You need fancy hotels, a good airport, nice restaurants and shops. Going to Vegas is not only about gambling, but also about all the goodies around it, like great dinners, awesome pool parties, nice clubs, etc.
You've been to Las Vegas? I envy you mate, it's been my dream to be in that gambling place but until now it's still a dream. If I have enough budget to go abroad, I'll certainly not miss that pace, it's alright to lose money as long as I can enjoy the place and feel the atmosphere inside the casino.
When you are into that place, you'll not only enjoy gambling but you'll also enjoy going to different bar. I have watch a lot of movies about gambling and saw how fun to be in Las Vegas, ever watch a comedy movie entitled the hangover, I want to experience what they experience, lol, it's a different level of fun.