There's no question that it's been a good investment, particularly if you bought at the right time.
How I wish I knew about bitcoin then in 2010 when its value was low to the turn that, with $100 worth of bitcoin has rapidly grow to $17 million at the current value. The question of the right time to buy is a very big problem. This is because, I don't believe anyone foresee what bitcoin value is as at today in 2010. And how many people were able to hold since 2010 till date?