You are certainly not alone
I myself feel quite worried even though I mostly moved my funds to Litecoin and the US dollar by now. I'm afraid that if some vulnerability found and exploited to the full, it may also affect all cryptocurrencies, not just Bitcoin. And the most dreadful thing would be if major exchanges start failing and falling. This SegWit2x thing looks like a Trojan horse to me since exchanges won't be able to decline it unless they choose to delist Bitcoin completely (even if temporarily). Personally, I hope that it will be postponed for at least half a year (if not abandoned altogether)
Why Litecoin? If the Bitcoin exchange rates crash, then that is going to affect all the altcoins as well, including Litecoin. And another thing is that when the Bitcoin prices crash, the altcoin exchange rates crash even more (percentage-wise). For example, if Bitcoin prices crash by as much as 50%,
then it is possible that the altcoin prices can crash by a massive 95%.
Faulty logic. First, if bitcoin crash 50% in terms of USD, then an altcoin (say coin X) will only crash 50% in terms of USD, if its value in satoshi doesn't change. Second, if if bitcoin crash 50% in terms of USD, and coin X's satoshi price is up by 10 times (because people fleeing from BTC and use it to bid up the price of coin X), then in this case, coin X will go up 5x in terms of USD.
Your scenario only happens when BTC crashes, and at the same time coin X crashes agaisnt BTC.