I'd rather believe Bitcoin's usage is the reason why became volatile. The volatility came when usage bring demand, which is making the price of Bitcoin up and down. Basically, Bitcoin usage is the root that create the value to the Bitcoin itself.

You can do tx with others without revealing your identity use Bitcoin. You can also use it to store your value and hedging against the inflation. You can also use it to get some yield by used it in some defi for Bitcoin. It's all create the demand to buy and sell for Bitcoin. In conclusion, Bitcoin usage was the factor why it has value atm.