I think it's relatively easy to con honest people because they tend to think other people have similar moral standards.

'we're inspecting your home on behalf of the government' [steal your jewelry]

'we're calling from your bank as there's been a problem with your account; we need you to read an access code from your phone' (steals savings)

'we're calling from your pension advisor as you appear to have been missold payment protection' (steals pension)

They're doesn't appear to be any need for dishonesty on the part of the conned.

It's possibly easier to con a greedy person?