^ You did not probably fully understand what is the function of BTC and how affects the price to become volatile.
Because BTC has a fixed amount and the price varied on the demand and supply in the market cap. Once the demand will increase, it means the supply becomes less which in turn to BTC becomes expensive and the price was pegged into a dollar-based value. Nevertheless, it is impossible that you mean BTC will become stable in price, the price will always be fluctuated due to massive traders of altcoins in BTC pairs.
Nope, Bitcoin price does not fluctuate because of a big number of people trading back and forth between altcoins and BTC. Bitcoin is so volatile because it is a pretty new asset class and investors are not accustomed to. They don't know how to evaluate it so the price moves mainly due to speculation. Nowadays we see big companies like Tesla and Microstrategy hoarding BTC as a hedge against fiat and for capital appreciation. This trend could change the violent moves of BTC especially on the downside.
Another factor is the low liquidity in the markets. Institutions with deep pockets cannot get their hands on BTC yet, but only with very low amounts that do not impact their yearly performance significantly. That's why you see investment funds like Blackrock only "dabbling" with Bitcoin - because they don't want the market to get in a buying frenzy.