Not a good way to make money if you only hold your bitcoin imo. Start trading bitcoin or altcoins to double your bitcoin and sell your profit to USD. I think that its good way to make money.
After doing trading it is not sensible that we have to sell our bitcoins for fiat/usd, but we have to wait with them for more longer and so with that we will also get the profit with the price rise also, we should have to think for long term investment in bitcoin as I think only that is the way to get the profit.
there are two kinds of investment: one is when you invest in bitcoin in short term or long term and sell it as soon as there is a rise to make fiat profit and get out.
and the other is when you invest in bitcoin to gain that profit but also gather more bitcoin for the future to "use" bitcoin directly as a currency.
so in each of these the way you buy and sell is a lot different.
i think how long you hold them depends on how much is your holdings. If you have a small amount, holding it for a long time is profitable but not that much that would have an impact to you life. It would be better to trade it actively to get a larger holding then that is the time you need to wait for a long time to encash.