We see things so important then we don’t care about dharma
“Busy for something” means we are distracted by that busy thing. So, these things, material things, worldly things affect everyone. Everyone is busy for those things. “[This is destructive] in part or completely to their own peace of mind, mutual respect, even belief in the law of karma;” means [one is] distracted by these things then it destroys the understanding or the belief.