The Devil is a smart investor. He likes maximum returns on his investment of time and effort. So, often, he chooses his targets very carefully. Bad people are already in the bag for him and he knows that.
So why should he waste his time with them, right? They will be only too happy to do his bidding. All he has to do is snap his fingers and they will come running to him like hungry, lovesick poodles. It is the good guys the Devil worries about most.
His biggest challenge is how to put them on a slippery slope: lower them a notch or two from where they are and send them to their downfall and to eventual perdition.