People nowadays bet more online than in physical objects - casinos, they are given the opportunity to bet in the comfort of their homes, without having to leave their homes and without the cost of transportation and accommodation.
When it comes to the cost of accommodation or transportation it wasn't such a big deal in the past. Flights and hotels to Las Vegas are very cheap compared to other cities, and in my opinion the price / reward ratio of the hotels in Las Vegas is very good. Nice pool parties, good food and night clubs and of course the big casinos. If you lose a lot of money in your vacation it is likely due to gambling and not the other things. And even if you don't like gambling that much you could take advantage of the cheap offers from casinos. I think that Covid played a big role in the success of online gambling. Before the pandemic there were a lot of people going a long weekend vacation to the big casino cities. All these gamblers had to look for an alternative during the lockdowns and went to play online from home. For me online gambling is very different to gambling a physical casino, I enjoy both and am glad that the lockdown period is over. Another thing that helped the online gambling boom is also the success of crypto currencies. It makes it so much easier to use cryptos for gambling online than Fiat money, it's faster and costs less fees to deposit or withdraw money.