Well at least you tried. If he chooses to ignore your advice that's his decision.
Don't sweat the little things like this man. Just brush it off accept the fact that he's gonna do what he wants, it's a lot less stressful than

. And when the shit hits the fan later on down the road and he ends up having to take it in (and spend $ ) you can sneak in a little "I told ya so..." But don't be a dick when you say it (That will probably make him less receptive to your advice), just be calm and state it as if you where stating a fact. Like 1+1=2.