Do people agree that holding altcoins are worthless than since everything depends on btc?
holding altcoins is not such a good idea. trading them is a much better one.
However, that altcoin could multiply a lot more than btc especially if that coin has a very low market cap right?
"can" does not mean "will" but yes they can get
pumped so their rises can be a lot bigger.
Also is it pretty much 100 percent that its impossible for the altcoins to increase in price if btc drops in price?
there is nothing called 100% and we have nearly 2000 altcoins there will be exceptions as there have been. if an altcoin is getting pumped there aren't much that can stop that.
So if bitcoin hits a huge number, would that mean all these altcoins at the moment would at least multiply at least the amount btc multiplies in value?
no