Fluctuating Bitcoin prices have become a daily complaint of Bitcoiners around the world. there is one factor that influence the rise and fall of Bitcoin prices such as the small volume of Bitcoin spread across the network
I don't think a sensible person would complain about the volatility of Bitcoin, because it doesn't do any harm to you as long as you know how to use it positively. Of course if you panic by seeing the price dropping and sell all your coins you will sit regretting it later on, but if you be patient, buy a little more if you have funds, and wait for it to rise again, you will have your returns eventually, and you will not need to complain about it.
To OP, the price of Bitcoin depends on the market movements, i mean the trades. It all depends on supply and demand, where if the supply is less and demand is more, it increases, and when the demand becomes less, the price decreases to an extent.