The most likely issue is what you said, that printouts are easily photocopied and distributed, so first in the door gets it. Your other issue is that QR codes rarely work on paper. The venue I work for doesn't accept them (a. because of the photocopying and b. the QR code is too large for the scanner). Scalpers here always ask for cash so they can't be tracked. Worth a shot since you already bought it, but venues also release the promoter holds the day of the concert at the box office, so worst case you could probably buy a new one then.