Live and learn, most traders will lose their shirts and learn from their mistakes before becoming "successful" at trading for the long run.
If he thinks that it is not worth it to learn and stay with trading as he lose 40% then what's the deal with it? I know those people that are not giving up are the ones that are becoming successful in the end. But not all the time we as traders can't endure it the losses and mostly we will just give it up and just put our hands up.
Just giving up without taking efforts to correct the mistakes definitely will lead to losing those 40% for ever. But coming back with strong technical analysis and a perfect trading strategy definitely will lead to big success in near future.
I will never recommend to give up but stopping for time being must be a requirement for any trader to correct his mistakes. Without taking any break might be leading to further losses. That will be more frustrating than stopping for time being to gain knowledge on how to avoid losses.