You can't monetize invitations because the guy that sells you the invitation could take the money and then kill your identity and also steal your stake during the first 3 epochs
That's the whole point glad that only one guy has this mindset of selling a code, we should educate people and ask them to undergo a test first before trying the actual verification, but not selling the code to them it's an invitation to scam people and it will give Idena a bad reputation in the community and it's a bad start for us.
Everyone who owns invitations can do whatever they want with them since this is the role of ownership.
Don't get me wrong, I don't like it either but it is what it is and you can't stop this or ban it.
There will be always nice people giving them for free, so no one will buy them anyway.