I'd wager a fairly high percentage. It's a matter of degrees. Crack addicts don't usually start out as crack addicts. There are gateways to becoming a a crack addict, right?

Again, it's kinda the same thing. There are things, choices, that get you there. And anyone can stumble down that road via a series of bad choices from failing to consider broad consequences to those choices. It is very easy to talk oneself into some things, choices, when one is in a vulnerable mental state (for whatever reason) and convince oneself that they are doing no harm when if they looked past their own nose and past that one moment, they'd see it's a bad choice and there WILL be consequences.