Of course for a scam to happen there need to be two parties involved - a scammer and a victim. The scammer is to blame for scamming, he clearly is the bad guy. But the victim is to blame for trusting someone without sufficient reason (I won't go into the clear stealing situation where security was present but subverted).
With Bitcoin, you alone are responsible for your financial safety. Unlike Paypal or other payment systems where you as the buyer can reverse the payment if you've been cheated, Bitcoin (and similar cryptocurrency) payments are final. I think there are good reasons that payment systems have an "undo" mechanism, and if you need such a mechanism, such when dealing with unknown sellers, you should use an escrow which allows you to reverse your payment if you don't receive goods. It's just not built into Bitcoin, so you need to arrange for it out of band.
Onkel Paul