Personally I feel that anything other than a very short term investment with altcoins is highly risky. Most altcoins are very influenced and affected by Pump & Dump schemes and unless you are able to watch the market for your altcoin holdings nearly 24/7 you are likely to miss out on the highs and lows.
+1 to your points, I generally consider most altcoins to be only short term investments, i know there are some people who hold altcoins, but honestly I can only feel comfortable if I'm holding an altcoin like ethereum, and prolly a handful of others, the rest are more or less pump and dump coins, and will not hold their value for the long term. Bitcoin is different from all of them, that's why it's possible for it to rise and plunge and then rise again, Bitcoin is definitely bound to cross it's ath very soon, it's great for BTC holders to see it gain traction all over the world, and with the kind of adoption Bitcoin got this year alone, it's growth will continue non-stop.