Here's my take.
Every great discovery, throughout the history of mankind, is weaponized. The internet is no different. The internet is a battleground and the hackers are the soldiers. Anytime you post anything on the internet, no matter how secure you think the site is,that information is vulnerable. Whether you're buying something on Amazon, or posting a profile on a cheater site, you're opened up to attack. You are trusting that the site is keeping your credit card info, or your private details, or kikny fantasies, secure. The hackers want to attack those details and use them against you.
Now, if its Matt from Kenmore with nothing to gain from being exposed,then who cares, hackers, or anyone else won't bother with you. But if you are the Chief of the Federal Family Values committee posting on a cheater site, you are fair game, and will be attacked and potentially destroyed for even the slightest discrepancy.
Keep that in mind, when you have a kid, and your wife starts posting pictures of your child on Facebook from the first day you bring that child home, to family vacations, to first day of school, and so on. That in 50 years, when that child is grown and older, that the information will still be there. And potentially, and most likely, that the information will be there to sell to the highest bidder. If your kid has nothing to lose, then who cares, but if the child grows and gets a position of power, that info will be used against them.
Don't do the crime if you can't do the time.
Skynet baby, Skynet...