You shouldn't guide people along on their sin in any case, I believe, since you're still involving yourself in the perpetuation of evil. That'd be like me giving up on a drunkard and saying "Welp, since you can't beat it, here's some instructions on moonshining." I find it amoral.
Tell him to stop being such a whiny, envious little bitch, perhaps, since he's obsessed with his self image to the point of where he thinks life'll suddenly work for him if he succumbs to his delusion. The truth is all that matters because truth is perfection since it is the absolute reality of all things that God created. Delusions, meanwhile, shouldn't be poked at in any direction.