[jrockway]

You can't really prevent "I stole your phone just to cause chaos". What Apple did with Find My was to remove the financial incentive to steal phones. What Apple does with this is protecting your iCloud account from someone who knows your passcode. (I would imagine that most people in relationships know their partner's passcode. Sometimes relationships sour.)

What prevents "I stole your phone just to cause chaos" is the risk/reward profile. Even though your phone is useless to someone that stole it, it's still theft, and you'll still have to face consequences if caught. If the incentive is "I'll be able to buy $1200 worth of shit", then people are probably going to take their chances with getting caught. If it's "I'll get nothing except the satisfaction of smashing someone else's electronics", then most people won't take their chances.

With the whole "knowing your passcode doesn't help" situation, it makes the long tail crimes even more difficult. "Tell me your passcode or I'll shoot you" no longer works, for example. It makes the crime significantly more difficult to commit, and requires committing crimes that carry significantly longer sentences. (Armed robbery turns into kidnapping. You could be looking at the rest of your life in prison for $300 in someone's checking account. Not worth it to most people.)

At the end of the day, there is only so much you can do. The rest is your insurance company's problem. The fewer viable attacks there are against you, and the less often they happen, the less your premiums are. (I actually don't know if there is insurance for this. I should check.)