I think that altcoins usually reflect the price of Bitcoin. When Bitcoin is down then typically the altcoins are down. When Bitcoin is up then typically the altcoins are up. If Bitcoin collapses then all the altcoins will probably collapse as well. The only circumstance where I don't see this happening is if another cryptocurrency rises to the top and Bitcoin falls apart. That new cryptocurrency would act as the new benchmark for all the other cryptocurrencies. In this case, altcoins may be affected in the short term, but would continue on their way as if nothing happened.
This is perhaps the most interesting theory. We have all seen the graphs - when BTC falls, alts fall with it, often magnified many times in regard to price and market cap because of the relative lack of confidence in altcoins. What is even more interesting to look at is
what coins do not follow BTC when it falls. Example: Two days ago, I was watching BTC fall between 3-6% and all the altcoins 24hour%change go with it. I was scrolling down coin market cap and saw something interesting - ARK was posting a -2% 24 hour change, but the graph was steady, even increasing a little bit. All the rest of the altcoin graphs had the same dip BTC had, except ARK. The question of "why?" then has a couple possible answers:
1. The ARK community is following a signal that overcomes the overall depression of the market caused by falling BTC price;
2. Exchanges are manipulating the price;
3. Some other party is manipulating the price, or buying significant amounts because they know something the rest of the market does not, and/or;
4. ARK does not follow the musings of BTC price.
Out of all four of these theories, #4 is the least likely to be true. Therefore, the price is going up for a reason, and is very possible depressed artificially because of people who are selling and DON'T follow signals others are following. If this behavior persists beyond the BTC depression on the market, what is the actual rate of increase we should expect from ARK in a positive market? Well, we have that answer.
During September 9th, Bitcoin fell considerably. ARK, however, posted a ~3% increase after all was said and done. BTC dropped 7%. But when the day of the 10th begins is where it gets interesting - BTC was fluctuating between a low of $4120 USD and a high of $4364. Up until this point in time, BTC has been bouncing around this range (@ 4219 as I look at it). As soon as BTC had an upturn, ARK started a steady climb. From the 10th till now, ARK has had an ~24% price increase.
BTC posts -7%, ARK does +3%.
BTC posts +2% gain, ARK does +24%.
This is what I find to be most fun about Crypto - finding the weird signals that go against the goliath which is BTC. Why? Who the fuck knows.