Investing in bitcoin is a risk, as the value can crash tomorrow.
I'm holding too so far, I believe in what bitcoin represents, so I'm taking the risk. Don't invest more than what you can afford to lose however, but if you can, you should buy more.
Also have a look in other cryptocurrencies.
Investing on bitcoin is one thing we could deal with once we have bitcoin or a good number of bitcoin. Yet, it always have a risk where in reality all types of investments surely does have a risk in a factor gaining profit. So it would need our full support for us to have or to earn bitcoin and to gain profit out of our transactions, investments and tradings.