Security is a very two-sided concept: on the one hand, it shields systems wanting to be closed from being accessed by outsiders, but at the same time there is security in numbers: a single party may be easily fooled, but a group of people who work together usually have a better chance of surviving attacks.
In the current world of crypto-currency the idea of a trusted party is being overturned, as currencies like Bitcoin and Ether become freely tradable and no longer require banks...