This is why altcoins are only good for short term investment because their prices don't seem to prolong its increase, and would all of a sudden dump its value due to some negative market effects, thus they are not suitable for long term hodling.
I believe you will disagree with my following opinion that is, altcoins are for speculations like short term or medium term speculations. I disagree to consider altcoins, most of them, as investments even you said short term investments.
I also disagree on the stance of short term investment. Investment, in my opinion, should be long term. If it is something for short term or medium term, it is more like speculation.