We're in a capitalist system, the price you pay the scalpers is the "real" price of the concert: it's the law of supply-and-demand.
Now, if scalpers win every time, this is an issue with the original ticket sellers, not the scalpers!
If Shell started selling petrol at half standard price and some guy comes round to fill up a tank and then sell it to people at 95% standard price, that's Shell's mistake, not evil behaviour on his part.
The existence of scalpers is curious. Artists could get the money they do. There are reasons why they still exist, one of them being that artists use scalpers to get cash in hand.
There is a really good episode of Planet Money that looks at why there are scalpers, how they work and what can be done by artists if they don't want them to make money:
They are speculators. People have instinctive dislike for speculators as they produce nothing and in scalpers case provide no benefit (such as liquidity) to society.
Speculation is just another word for betting, I don't think that's an inherently bad thing.