I kinda wish I knew what you were eluding to, but I have a feeling you're being cryptic for a reason.
Ultimately responsibility for a person's actions lies with the person. If the cake is eaten, the fault lies with person that ate the cake.
Does that mean you should trust people to not eat your cake? Absolutely not. People make bad decisions all the time. Just cuz it's not your fault that somebody ate your cake does not mean you shouldn't take action to protect your cake from being eaten.