Those are rookie numbers. The Monero users are, by far, greater in number than Coinjoin users.

And no, the anonymity set of Bitcoin is not greater than Monero, just because it might have more users. The overwhelming majority keeps them on exchanges, under KYC, and from the rest, the majority of the coins are simply kept on a self-custodial wallet, without any privacy enhancements apart from coin control. A brief look at Bitcoin's current privacy options makes this clear.