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.
You should only choose one way of investing in this market and short term investment should be more encouraged during this time. At the moment the market is still unclear and there are many big risks so it should not hold for too long. I personally do not have much patience when investing and will sell when it is profitable because the bear market is still going on and people will still face many difficulties in the near future.