There is more than one way to skin a cat.
Short-term traders or long-term investors both have the same goal, namely to make money. As a trader (as opposed to investor, though I also invest longer-term in some cases) I once, years ago, did a test when trading Apple stock -- at the end of a single test day I captured more gain trading both long and short than Apple stock made for the day. I consistently did that day after day with the same result.
The point is, whether one invests or trades is really simply a choice of method used to reach the same desired goal -- that of obtain profits in the stock market.