Who do you think are the higher rollers...
Gamblers online at bitcoin casinos.
or
Gamblers that play at physical casinos ?
Finally, why do you think that physical casinos attract more or less people (excluding the fact that bitcoin is not mainstream)
Of course the higher roller is the physical casino because everybody has physical money than bitcoin. But the easiest and convenient way to play casino os thru online, you can just play at home.