There are some altcoins that have strong communities and investors. there are also some altcoins that pair into dollars. so when the Bitcoin price drops it does not have much effect on the altcoin.
Yes its true but many altcoin will be affected by the price drop of bitcoin as well. But as far as I know most of altcoin selling price follows the bitcoin, when altcoins price high then definitely bitcoins price will be higher than altcoin.