I would also like to make a separate explanation on my idea since you did not fully understand it and i think it would be really nice feature for Events Booking. Feel free to use it in the future if you want, this is not a feature request.
I got this ideia on an event where they use something called POAP. Please visit this website to try to undestand their concept:
poap.xyz/
This would be great marketing tool for recurring/repeating events. So how would i suggest this works: forget the NFT stuff POAP works with as we don't need it, just create for every event a unique QR Code. That QR code would be only scanned by attendees in the venue (somewere printed or in a screen but never online) so they could collect their "proof of attendance". Here we put the scarcity value of the NFT's because the QR Code is only available for people that went to the event.
This would create a data base that could be used on the user side for them to collect their "Attendance Badges" and achieving milestones like attending 10 events or never missed 5 consecutive events. This would be another fun user experience along with attending the event itself that they could show off and share on social media.
On the event organizer side, this data base would give the ability to create promotions to the most loyal costumers. I.e. a voucher for some milsestone or if they collect x number of "Attendance Badges" or simply, because you collected a badge on last event, here is a discount on this one.
There could be Modules to show users ranking in order to spice competition or some client area page where they could see and share their "achievements".
So to wrap up: an attendee scans a QR Code at the event and collect their badge. Later they can acheive milestones and all this shared in social media. Event organizers can engange loyal customers and create some competition between them also rewarding them with some discounts.
You don't need to answer this post, just come here in the future if you want to use this idea.