Tanjamaltija
You do not decide whether or not someone can afford to lose money. It is up to the other person whether to offer you the ticket for free, or at half price, or at full price, for someone else, because you have not actually paid for this person's ticket, and you always have the option to go alone.
I think it's possible that the OP gave us that information - about the friend being well-off - as context to the situation.
I'm sure a few posters, considering their response, would've asked if the friend could afford to give the ticket away before making a comment.
Of course the friend is not obliged to give the ticket away for free, and yes the OP naturally has the option to go to the event alone; but it doesn't appear to be the case that she wants to do that!
We can only judge by what we'd do ourselves I guess. I'm with those who feel that if you let your friend down in such a way, you donate the ticket simply as a good-will gesture. I suppose it depends on the nature of the event but most people I suspect don't want to go to 'events' on their lonesome, which is why they plan to go together in the first instance.