I find it strange when people say they won't invest in BTC as the price was once a $1. Surely people can recognise the price was that low because people didn't believe or understand it then (risk and return). Microsoft, Google etc.. were once penny stocks, however you wouldn't have an issue holding these in a portfolio. When you talk to outsiders about Cryptocurrencies nobody has ever heard of the altcoins, however they may have heard of BTC. In addition, miners sell the altcoins to buy BTC or LTC (they clearly doubt the medium/long-term prospects of the altcoins).
If you are to buy altcoins don't get caught up in irrational exuberance. Monitor the highs and lows of the coin and try to buy low (observe the exchanges for a day or two first).
How is Bitcoin any different from altcoins, other than being the very first cryptocurrency out there?
Less volatile (easier for businesses to trade with. Which is essential if it wants to be seen as a currency), larger market capitalisation (therefore harder to exploit), greater trust & media coverage, sensible period for halving of block chain and most importantly it has survived longer that the rest. Basically, considerably less risk for the investor.