This was such a labored comparison that I'm unsure how you even made it with good conscience.
That you can't see the analysis is likely the effect of bias.
Do the math on the credit card analysis. Typical bonus is that you spend $3,000 to get 50,000 points (or $500). Credit cards charge of fee of approximately 2% for using the card (i.e. fee to the merchant). $3,000 times 2% is $60. $60 received for a $500 benefit paid out.
What's the profit? They're counting on you not to sign up just for the bonus and to continue using the card. Indeed, there is often a term of service saying exactly that. You violate the express terms of service of the contract that you agreed to by getting the card just for the bonus, because it is money losing proposition for the bank if you just do that.
So, again, you (general you, not personal) believe it is okay to violate the terms of service of the credit card agreement to ensure that you get a benefit that costs the credit card money and for no other purpose than to get that benefit? Since the credit card companies--as you state--are not in the business of losing money, they pass the costs to other users in the form of higher interest rates and fees. So gaming the system was only for your benefit, at a cost to others.
Now let's look at the scalpers. They buy the ticket that the artist/venue agrees to sell at a price (probably with a term of service that says the ticket can't be resold for a profit), then turn around and sell the ticket at a higher price, thus ensuring that they get money by taking advantage of the system, at an additional cost to the other people who do want to see the concert and they pay more as a result.
Both people took advantage of the system (both probably in violation of the terms of service in the agreement), made money by taking advantage, and ensured higher prices for other users.
The situation is mathematically identical, and probably morally equivalent. Indeed, the scalpers might have a slightly better argument that they add value in that they bear the risk of possibly not selling some of the tickets (or selling at a loss), thus ensuring that the original seller sells those tickets at the face value without taking the risk of non-sale. The credit card hacker knows he/she can stop as soon as get the bonus, so no risk of loss and no benefit to the credit card company.
Still can't see it? Math it out and see how you can argue that the credit card company makes money off a person who does just enough to get the reward, doesn't pay interest, then moves to a different card? Argue why it's morally superior to do so in direct violation of the terms of the credit card company terms of service but not to resell tickets in the same fashion? Figure out who bears the loss in each of the examples.
The fact that you reached the judgment above (that I had not made the comparison in good conscience??) without working through the logical analysis is likely the product of bias. That bias is almost certainly that you credit card hack, you believe you are a good person (most people do), and you therefore conclude that what you've done is okay (even if it violates the express agreement you had when you signed up for the card) because . . . reasons . . . (really, the reason is just that you believe you're a good person), but what scalpers do (and almost certainly you don't scalp) is bad.
There's a great book on this dynamic by Dan Ariely called "The Honest Truth About Dishonesty." What it highlights is that pretty much everyone cheats a little, but only a little because we all want to think of ourselves as good people. So we rationalize our actions to stick with the conclusion that we're good people. That is the norm.
So, yes, I made the comparison in good conscience because it's supported by logic, it's rational, and the conclusion follows from the premises. The reason I made it is because we address a lot of irrational behavior on this forum and it struck me as odd that our gut level reactions to those two examples is very different, but the analysis of what's really going on is pretty much identical.
Edited to soften tone.
