Looked at altcoins and they've started rallying pretty hard all at once, whats the reason for this? Is it because of Bitcoin going sideways for a decent while or some other reason?
It is caused by bitcoin moving sideways for a while, which led to a big pump on bitcoin's price.
When bitcoin gets pumped, altcoins historically have also gotten a lot of increases in price and market cap. So that is the reason for the rally. I do't think the bear market is fully over, so take your profits wisely now that the price is a bit higher.
Altcoin prices will continue to depend on bitcoin prices since it's the face of cryptocurrencies and #1 in market cap. So if bitcoin is in a bear market or is getting dumped, so will altcoins, and vice versa in a rally.
That is correct. We have two patterns already for altcoins. The first is during waves of Bitcoin either rising or falling, which all alts follow. And then when Bitcoin trades sideways, altcoins take this chance to rise up against each other, but generally recovering all their values lost against Bitcoin. I do not think this is the end of the bear market either. So I also took profits today (did not want to wait longer).