There's between 100 and 200 (sometimes more and growing) million USD equivalent daily volume for XMR, and that's only on CEXs. We have DEXs, p2p and trade for goods as well.

XMR did dump by 50% to BTC when binance delisted. It has since recovered 50% and is on it's way up still relative to BTC. Binance and other CEXs were trading XMR that didn't exist (nobody should be using a CEX that doesn't publish the viewkeys for their XMR reserves) and then when they delisted they disallowed withdrawals, forcing people to sell for something else. It should not have recovered if the price weren't due to deliberate suppression, yet it's recovering as we speak. i expect it to perform well in the coming years relative to BTC, possibly outperform it.

If you want to buy XMR, kraken is good outside the UK, and there's always Bisq (for BTC) and Haveno (for fiat).