I'm 40 years old and still going to see concerts. I'm seeing Judas Priest and Slayer next month. I also saw Ozzy Last August when he was 70, and had a great time.
If you like the band, and you're into their music, you have nothing to lose. Its going to cost you, what, like $40 or less with groupon. And what's the alternative, sitting at home watching TV or something like that? So you go, have a few drinks, rock out to some music you love, I see no downside.
Worst case you have a just OK time, but at least you can say you took the opportunity when you had the chance.
I'm older than you and still love concerts. Although they are not like they were back in the 70s & 80s.