"The bitcoin market is too volatile and unstable"
So are the forex market and stock exchange market.
Bitcoin has the least volatility in all the cryptocurrency except stable coins such as USDT, USDC, BUSD, and etc. But if you compare Bitcoin to forex market we can say that Bitcoin is so volatile especially if you used to trade forex for a long time. Aside from that, most trading pairs in forex market are fiat which is stable, that's why they used "lots" to earn huge profit even with a small movement of the price.