> Your friends were acting in the wrong and in the aggregate they did harm the market

Please explain this harm to the market. I don't see how the market was harmed in any way.

> They create scarcity in the primary market, which forces people into the secondary market.

There exists scarcity in the primary market, because otherwise there would be no benefit to buying the tickets. That's a fundamental misunderstanding you have. Resellers do not generally create demand, they capitalize on existing or future demand.

> the same number of people would get tickets, but there would be a greater welfare gain for consumers.

Define "welfare gain". I contend there is also welfare gain for consumers with a secondary market, but not necessarily the same consumers. The primary market prioritized people that are available at certain times and have money available at the initial sale time. The secondary market prioritizes people that may not have been available at the initial sale time at the cost of a more variable cost.

You can contend that your group of consumer is better or more worth than the group I've defined, but if that's your goal, please do so. Otherwise, a secondary market provides access for at least the same number of people, and sometimes more, as it's possible (and likely) that while some tickets might go at a premium, some others might go at a discount because of poorly executed strategies by brokers.

> They may be taking some risk in their venture, but they're still not providing any value.

They are. That are providing access. Without a secondary market, after the last primary market ticket was sold, it would be impossible to buy tickets to that event. Even if you allowed a secondary market but somehow restricted it to only those that intended to go but could not, you would shut out all those that wanted to go but could not be available to buy tickets during the period it was initially on sale on the primary market. For some events that's as short as a few seconds (and yes, even without brokers).

> They are needless middlemen in a market that already sells direct to consumers.

So is Amazon. So is your local Supermarket. So is any fresh fruit or produce market for that matter. I mean you can just drive to the farm, right? I hope you only like your produce and fruit in season, because people that warehouse it to sell at times when the market isn't flush with that product are just needless middlemen in a market that sells direct, right?

> Presumably they are claiming a bigger share of the welfare pie than they are giving, else they wouldn't be participating in the market.

If all you prioritize is cost, then you're not serving people very well. The very nature of a market is that the many diverse needs of the buyers will be served by different sellers that offer slightly different incentives for different costs. If we only prioritized for cost in food, we'd all be eating rice and beans every night and that's all that would be grown. Instead people prioritize taste, and nutrition, and health, and we have an actual market. If we only prioritized for cost in vehicles, we'd all be driving either a bicycle or a stripped down motorcycle, because who cares about comfort or safety?

> The market system is theorised to be the most efficient means to allocate this capital.

The market system is theorized to be the most efficient means to alloow buyers with diverse needs find a seller that can provide those needs. Sometimes that's cost, sometimes it's something else.

> The scalpers don't serve a social purpose

I've outlined some already above. To repeat, they provide liquidity, meaning there is availability of tickets at a cost people are willing to pay more often than without them. They provide the ability to find the true value of a ticket at any time, rather than the fiat price that was offered initially. This can mean that tickets are available for cheaper than originally offered for (see my real life example noted earlier).