If you are trying to see where you should be selling, that means you are not going to really be a good investor, just focus on being a trader if you want to? That way you would basically buy and sell depending on whatever you think you should be buying and selling.
all of us have goals , that's why we have Target price on where we will sell . Entering here without a goal is hard because you can get confuse and you will only sell on random times . Being a good investor is how you follow your plan .
You can't say that we should trade instead of investing because why if investing is our passion and there are people that believes that trading is hard .