Yeah I'm sure there are. But I'd imagine a much lower percentage are taking it serious.
Not too mention all the players in the US are spread out over a giant landmass which means that meeting players of similar skill level to you and growing in the game becomes harder.
That's why the pro scene for both Brazil and NA is almost entirely located in Southern California. Few outliers of course but most of the big names (c9, Liquid, MIBR etc) are there. It's not just CSGO esports though. Southern California is where esports happen in the US period.
Also following the logic of the original post. Russia and China have much worse scenes then the US. They would be 2 and 3 in terms of total player base and one top team. Both countries have the same geography problem the states has however.