With both buying an account and buying a copper membership, there is no guarantee you will come out on top if you buy either of these with the intention of using them to scam. If you buy a member account (or a copper membership) with the intention of using this to scam, you will need to steal at least $20 (or $40) just to break even, and if you do not, the value of your investment will presumably go to zero when your scam attempt is exposed, and receive negative trust. In both cases, one can presumably make money in non-scamming ways.
If you are only comparing the price... if the title gives them a better chance of successfully scamming for more money, it could be worth the increase?... especially right now when it is a new rank and not even listed or really explained anywhere except this thread. People send coins to accounts that create a new account with a similar name to an escrows or another trusted member, now they have the option to get a new rank and allowing them to put even more spin on how their account is "trusted".
The potential to scam people by creating imposter accounts has decreased due to the content of PMs being sent by new users is not sent via email anymore. Also the cost to create an account called "thermos" is free, while the cost to create an account called "thermos" with a copper member tag is around $40.