Well as you are saying he/she is making a lot of profit how will they can have lose? Dear in the space of cryptocurrency, each step matters by the traders. let's assume as you said he/she is making a lot of profit right? In any case that specific trader fell prey to greed which is the worst foe of humans and started to take over trade which is a bad habit so these kinds of actions can destroy traders portfolios.

After all that, there are a lot of aspects crypto user have to keep in mind if they have big portfolio which includes they should not click any of the useless links these links can be phishing links and they should not download any kind of open source software/Application into their device. Security also matters here in crypto space so always try to store your secret phrase in a private space so that no one can access it easily. You need to keep secure yourself at your own end your one wrong step can lead you to zero.