They just walk the frontier of price-time preferences. And time preference is just the same as any other preference. For people with high time preference and low price sensitivity, scalpers are good. If tickets were auctioned it wouldn't be a problem. For Electric Forest you get an early line if you've been before, which you could turn into either a separate auction or a discount.

Scalpers that corner the market can do things that are bad for everyone but them, of course, but till they have pricing power they provide utility to buyers.