I think good investors are investors who get a profit and they never stop, and also good investors know what to choose and they know when to stop and how much to invest.
only a few investors can always benefit like that because every investor has a different strategy and not always the steps that investors take good, sometimes they experience a lot of losses.
It doesn't mean if you are an investor you will always get a good profit, sometimes the market is not on their side that's why they always have a hard time to manage their profit over losses. Enough knowledge about the market is a very important aspect here or even more on that so that you will not having a hard time to analyze everything.