In the year 2011 Bitcoin was below $10 and now 2015 Bitcoin is at $114k. This incredible increase in the price of Bitcoin speaks volume so yes it is still good to invest as I believe it would be 10× more the price in the next ten years. It is the perfect idea because you are thinking about holding in the long term goal and that's just awesome,  bitcoin's price is rotational that's a fact but it has also proven itself over the years that it is worth investing in, I have seen online predictions for Bitcoin that it would reach the price of Gold in ten years time and I'm saying that it may not really reach the price of Gold's market cap at 21 trillion but it will definitely be 10× profitable.