It's a bug. theymos already addressed that issue/bug on another thread:
Simply read and follow the second line:

thanks for the help!

Yes, you can, it works for any rank. You get the option as to whether you want to 'wear' the rank of copper or not after purchasing it. As you already noted there's not really much benefit to a Sr. Member but some people just do it as an alternative to making a donation to the forum.

It means now we can use avatar campaign in the bounty. But what is the requirement of enabling the images in the profile. Newbie can now turn to Junior member in 30 days.

Can we pay also a small fee for merit as a starter? Just hoping. It's like one-time transaction for newbies or newly Jr. Member to have merits and the fund will go to the forum...

Why don't just close alternate crytocurrencies then or disable everyone signature, if not we just create the problem and then introduce a solution and then another problem comes out of the solution itself, create another solution.

Why don't just go to the root cause and stop it.

Merit selling, merit abuse, merit farner, merit gossiping, merit harrasment, merit bullying

That is not the right calculation here, ealier on
If the amount that will be collected from ico spammers will be tiny comparing to ads then why would we need the alternative cryptocurrencies at all where all the ICO spamming is happening, just close it and why would we need signature which one way this ICO spammer thriving here.

The question is why need signature and alternative cryptocurrencies at all? what is the reason having to keep it despite its bring disaster to the forum and there is no monetary gain keeping it in the system.

I just noticed mprep has Diamond Member tag on his profile, also hilariousandco with Gold Member
did theymos ever explain about this type of 'member'? these don't seem to fall in the same field with copper member
copper member listed as Position, while Gold/Diamond listed as Custom Title


His post explained and pointed clearly the reason behind this copper membership creation
some other members bought it just for vanity reason

I would support Mr. Cassio's suggestion, but it may be complicated to track if someone transfers their accounts to others.  I do, however, agree with the concept that any paid upgrades should be sufficiently high in cost as to deter their use as a vehicle for spam.  A fair price for a fair service.  Perhaps removed from an account upon any spam violation, no tolerance policy?

I think the merit system is a great approach to cutting down on spam, over time that should have an increased effect.  It will be great when the Bitcoin Discussion forum isn't filled with the same 20 items just tumbled around in a new combination of lexicon.  If you dare, as I have, to actually respond to some of these threads, you're confronted with masses of people that frankly, I don't know how they get on the Internet, much less posses any Bitcoin.  But hey, I never cease to be amazed at all of the variety that is "out there".

Best regards,
Ben