Conflicted on going to a concert with a friend

My friend has a habit of buying 2 tickets to events, festivals, concerts, etc without asking if anyone is interested, she just expects to always find someone that will go with her. She bought tickets to a concert that is happening this week, asked me months ago if I would like to go and I told her I cant stand that band. No problem, she’ll ask someone else. Well now it’s in a few days and she hasn’t found anyone to go with. She’s now asking if I’d go and I wouldn’t have to pay for it. She’s just wants someone to go with her. I’ve been told my whole life that “I’m too nice” I let people walk over me, I let people talk me into things. So I’m struggling with staying firm and not going or would I feel like I should be a good friend and just join her. There’s a whole backstory too; how this person isn’t really a good friend but she’s gone to concerts with me that she didn’t care about. Just curious what others would do.