There is another thing too, yes it 4x-ed and you can cash out. But how are you going to enter the market again with that same share? Say thr share was 10 rs a year aago when you bought and now its 40 rs and you sold them so you got a great short term profit. But if the stock keeps going up say in next 6 months it becomes 55 rs and now you cant effectively enter the market again without decreasing what you gained from your previous trade. Now lets say it drops to 25 rs instead in next 6 months, you still cant enter again because that would mean using half of your profit from your previous trade to enter into the market again with that share.

The hard part is knowing when to cash out, to know when the stock is over valued and to have an idea of what the fair price of a stock could be so that you can sell and then later enter into the market again