It's all relative.
Lucha Libre is clearly an attraction in Mexico, but it's a niche facet within a semi-niche sport. When Mayweather/McGregor are running an expensive PPV, to a worldwide audience, it's to little wonder that they drew so much more (Triplemania grossed a ~$500k gate). Yes, money-to-money, I agree that a wrestling show will most likely never draw those figures but, within equal parameters/fields, Wagner did pretty damn well for himself. I'd wager even better if it was Parka/Wagner instead of Psycho, too.