I believe you have totally misunderstood the correlation between Bitcoins and Alts, if you were observing prices you would have noticed that, as and when there's a rise in the prices of bitcoins, a similar kind of movement is seen in the alts market.
Altcoin moves up only when bitcoin prices are stable or less volatile. But when bitcoin prices move up or move down mostly altcoins goes down because if bitcoin goes up people move their funds from altcoins to bitcoin and if bitcoin goes down then in a panic they less even faster altcoins.
However there's something you should know, whenever alts crash they do not recover as fast as bitcoins does, so investing in alts is a huge mistake unless you're sure what you're doing.
If you invest on a good altcoin then they may go up even faster than bitcoin but it all depends on what kind of coin one is holding.
In my experience with Bitcoins and Alts, I have always seen that whenever alts take a beating they take long to recover, whereas Bitcoins starts it's recovery faster, primary reason is traded volumes, sentiments of the community, which will always be higher in bitcoins than alts. Hence blaming bitcoins is wrong, Bitcoins is the original crypto and you should focus on it, if you already have alts then simply hodl them as their recovery will take quiet a while.
I do agree that one has to hold altcoin instead of selling at losses but make sure it is not a shit coin. There is no point in holding shit coins for long.