Altcoins, too, can see the same amount of growth in a short span of time. The thing is, can it sustain it? No, and as initial investors of the said coin already profited enough, they'll plan their exit and watch as poor souls who actually believed the project cry out for help holding their bags. This has never happened with bitcoin, even though there were tons of fear-mongering related to its price for years on end.
If I'm not mistaken, there are a lot of altcoins that can really grow more than Bitcoin. But those projects could be just pump by some groups, specially that we have a lot of pumpers in the altcoin market. So that could only be temporary and then the admin of those pump groups are the one who's going to make a lot of money by selling early before giving the signal to anyone.
So for us, at least the majority here just stick to where we know that we can make money in the long run and that is Bitcoin. It might be hard to see the price during bear market, but as soon as we recover and then some semblance of a bull run just like what we have seen right in the last quarter of the year. For sure we will not regret staying in the market and hard grind of saving thru DCA.