For example Bitcoin was at 31,000 USD last year in summer, at 42,000 USD last year around christmas and is at 69,000 USD now. It is still very volatile.
To solve volatility, many people have bought so called stable coins.
They did not buy stablecoins because stablecoins are stable and Bitcoin is volatile.
They usually consider stablecoins as alternatives for fiat currencies than alternatives for Bitcoin. Rather than cash out Bitcoin to fiat currency and wait for chances to enter the market again through fiat currency, they take profit from Bitcoin to get stablecoins and wait. That's it.
If you interpret it as they sell Bitcoin to have stablecoins just because they want to solve volatility, it's not correct.
A stable coin is a stable coin because it is stable - not volatile. But when reviewing such a stable coin, we can spot many dangers:
Stablecoin is a name but whether its value (peg) is stable or not, it depends on its peg to a fiat currency, for example, the US. Dollar. If a stablecoin loses its peg, it is no longer stable.
This following report can give you some insights.
Stable coins: a deep dive into valuation and depegging.