I bought some altcoin whose value went down deep enough. I think if there is a drop in the market it's all normal. and if you have some knowledge of some altcoins, keep monitoring and doing something that can be profitable.

Looking on the charts the top 10 by market cap all of the coins had a tremendous bump in a very short period of time around this November-December time period, some of them look like a logarithm they're so steep.  This incredible increase in price in such a short period of time happened to a bunch of other alts also not in the top ten, Verge for example.  

This looks unsustainable and indeed it looks like a correction is occurring. Who knows how far some of these are going to fall? I would guess the ones that have a solid reason for being, that have true value and are being marketed well will end up doing a lot better than fluffier ones.

My question is what triggered the stampede to buy? I'm guessing it was more people, me included, who got exposed to this world through the bitcoin phenomenon, looked into a bit and saw these other coins and jumped on them along with bitcoin.  

Yeah, you never know. Some Alts are battling it out now anyway and some are trying to gain some huge relevance in the community. Nevertheless, this is the alts world and anything can happen to them within a twinkle of an eye when people are trying to quickly cash-in on profit and then trying to see how they can get the best of a high pumping bitcoin.

But when a new investor steeping into crypto world they are all being advised to diversify their capital across bitcoins and various altcoins hence we can expect alts to grow further and any crash happening may not sustain for longer periods. So, practically we cannot expect alts to crash again and again.

The most part of coins is controlled by big players, so that they can direct and launch panic, and also to merge and redeem coins in the market. so if it's profitable for whales, yes, coins will fall.

altcoins will rise and fall again and again, it is worth looking at the graph for the year.  need to learn to ride a roller coaster.

It is impossible to give an exact answer. There are many factors on which it depends and we only know it at the last minute.

Sooner or later there will be some kind of crash of altcoins and after that there will be another one and so on. It all depends on stability of bitcoin since every alt is in some way or another connected to it.

I think it could happen again, where the price of all altcoin crashes, in the world Cryptocurrency is nothing is impossible,
by selling all their coins the coin holders in large quantities can damage and shake up the price in the market...

This is the part of this market. You need to be always prapared for some crashes.