Obviously, as the more people before me, they said that is the difference in the exchange rate over the time. But except this, after a while one can have a significant amount due to just not spending his coins. Clearly for many people it's a way to put their savings in a safe heaven, though the crypto currency volatility, but without the fear of the inflationary fiat money.
Yes I agree, to get the maximum benefit we have to be patient for a long time (more than 1 year), based on the price movement from 2013 until now the bitcoin price always rises.
Keeping bitcoin for a year will give a great chance to acquire more profit it is not the best to enjoy best of bitcoin feature. For me. I can get benefit of using btc by it's feature of anonymous and fast transaction. As well as this is the currency i used to gamble.