Majority prefers holding because its very easy with no problems whatsoever. You just buy bitcoin and let it sit in your wallet. As far as traders today, I presume that they're doing some day trade or intra day trade, meaning they buy coins and as soon as its ripe for the profit, they immediately dump it within the day and go on the next coins. But you have to remember that there's a big risk doing this and only experienced traders have the guts to perform this trick.