> It's pretty easy to have a situation where the number of tickets available is higher than the number of people that would have bought tickets for themselves on day one, but you hit immediate shortages when scalpers are also buying.

But the total number of people buying tickets is the same, all that's happen is it's being temporally shifted for the gain of the people that can afford to do so. This only works because the actual offered price of the tickets if far below that real cost people are willing to pay. If tickets were initially offered at an accurate price, there would be no money to be made buying them for resale (well, almost. There's still the option for artist demand to change over time with popularity).

There's only a few solutions to a supply and demand market problem where demand far outstrips supply that actually seem to work. Increase supply, or decrease demand. This has actually been done by some artists and solved the problem. Kid Rock, for example is known to play a large number of dates at a location, inundating with supply to the point only the best tickets can be sold for appreciable markup. Like, in his home town of Detroit, I think he played between 7 and 11 consecutive days in a stadium. Other artists will add dates after the initial sale depending on demand (which often destroys broker profits unless all those dates sell out too).

> In a situation like that, scalpers are doing almost all harm. They add liquidity to a situation that already had enough liquidity, and extract tons of money in exchange.

How good the liquidity there was and how much harm the brokers caused depends on how accurately demand matched supply. If there were 1000 ticket and 1000 people would ahve eventually bought them, then the brokers didn't really help. At the same time, they probably aren't going to make much money, since 1000 people willing to pay $40 doesn't necessarily mean those 1000 people are willing to pay $60, and given that reseller exchanges charge about 10% of the sale cost, they need to charge a lot more to make a profit. Brokers don't tend to want to buy for events where they can't really make money, so they try to avoid these events.

Alternatively, if the event has more tickets than consumers to buy them, brokers don't want to buy those either. Sometimes they do, and they sell at below market, sometimes well below market, just to recoup some of their money (having 20 tickets of 1000 at the event you bought for $40 when there's still 200 for sale on the primary market when the event is in a week means lots of tickets for sale for $20 or way less).

Finally, there's events where there's a lot more consumers than there are tickets. Perhaps there weren't enough tickets at the sale day to sell out immediately. It would have sold out well before the event date though, because there are way more consumers than tickets. In this case, at that point liquidity would have dried up. Brokers provide liquidity over the lifetime of the event. That's what they provide, and for that they extract money. There's a debate to be had as to whether they provide enough value for that service, but it's false to say the event had "enough liquidity", as if there was enough liquidity there would be no margin for brokers to make money, especially not the 10% cost on sale price needed to make a profit on the exchanges.