There is a lesson about hubris, but most people miss it. The Devil's deal is false, he doesn't play "fair and square." Johnny wins the bet but still loses his soul to the sin of pride. It's even in the lyrics: "My name's Johnny and it might be a sin, but I'll take your bet and you're gonna regret 'cause I'm the best that's ever been!"

At least that's how I've always interpreted it.