I think some Alts drop the price too and many good alts drop the price more than 80%. I think its the same with bitcoin because as main currency in cryptomarket, its affecting to most altcoin price in market.
I think you Bitcoin is more stable than any other altcoin. Look at the Bitcoin volatility index to make sense of it as how volatility has reduced over the years. Check the charts here
https://bitvol.info/