Who decides if you're too old?

A couple of weeks back, I'd planned in a vague way to go to a local gig, to catch a young punk/folk Billy Bragg style singer playing support on a tour, but then I began to worry because I thought at my age, and at that venue, I'd stick out like a sore thumb!

I'm comfortable enough to go to open mic nights and small gigs in pubs, because generally they attract a wide age-group, both performers and audience.
Although I've not been to any, I'd imagine I'd be comfortable with the anonymity of a large stadium-size gig. For that matter, I've seen photos shared on social media from theatre-style venues, generally featuring a come-back artist on tour, where the audience members have looked FAR older than I am, and if I'd been able to afford to see Bruce Springsteen some time this last week or so, I think I'd have had plenty of company of my own age.
But it's the thought of that in-between size venue putting on up-and-coming artists, themselves often in their early 20s, and attracting an audience in the same age range, that makes me feel uncomfortable.
At the younger end of the age scale, it's easy to know if teens are allowed - there'll be an age limit clearly signed - but who should decide if you're too old? Imagine though that you walk into a club and everyone else there is half your age ... Will they think you've taken a wrong turn? that you're delusional about your age? or that you're only along because you're a relative of someone in the band? This is something after all that seems to apply (in my head at least) only to music venues. The other sorts of places I go - theatres, cinemas, book events - don't feel like they have this unstated age limit.

Long story short, I chickened out.


Then a couple of days afterwards, I saw this article  from the Independent - one of many being shared round the web telling a story about an elderly Polish couple who visited London and headed out to a nightclub. At first people assumed they were lost, but, no, it turned out they'd heard good reviews of the place and bought tickets before their trip!
Well, I've decided that if they can go out, mix with the youngsters, and have fun, then so can I! I shan't be off out clubbing - it's not my scene at all - but in future I shan't let my age stand in the way of listening to a band I want to hear.