I believe bitcoin will increase in value and that is definitely a reason to hold. However in the long term there is a risk that too many people hold and new comers won't invest in bitcoin, retailers won't adopt bitcoin, and then what is the point of a currency you can't use? Bitcoin needs to be available to buy and trade if the currency is to survive.
That's why bitcoin is really turning to be just another investment platform. At the beginning no one would thought that the price could go as high as $20K? And when the big whales and big boys join the market, suddenly the rules has changed. It now becomes a store of wealth.
But for us casual investors who have small amounts stash in our wallet, I believed that its better to hold for long term and not sell our coins. Because we are small and we want to really earn a huge financial profit. We can only see this happening if we will just hold and save some, but at the same time have a extra coin that we are going for trading purposes only and do not touch the coins that are for the long haul.