Yes you are right, bitcoin is indeed an investment. Holding your coins and letting bitcoins price goes up is a good tactic. Let bitcoin do its work and earn for more until you have enough and get yourself contented. Selling altcoins and buying bitcoin is a good idea.
For short-term bitcoin investments it might be bad, but for the long term I believe bitcoin can still give big profits. The conditions must be sure and believe, when the price fluctuates must be calm and hold until the price as expected. As an investment, bitcoin still gives hope.