Both short and long term investments have their own risk and disadvantage. The market is very volatile and it will be very risky to trade short except if you are really skilled then long term requires a lot patience cause you have to wait for the best time to sell so you will make profits.
Of course, short and long have the same opportunity to be profitable, if we make it long term, and buying top rank coins is a good and safe thing, whereas for short term, buying new listed coins can make us get a big profit.