Yes trading is a job that can not be predicted easily but you better keep the value until the desired increase comes to be traded.
Because trading in numbers can change in seconds, thoroughness and speed may be a necessary skill for traders.
True, when trading you should always book the profit you desire because that's how it works. If we don't book the desired profit then there is high chance of loss. If we are holding the value for long period then I consider it as an investment.