Rather a lot of oldies on this site.
I'm just passed 50 but still fit into the same clothes as 25 years ago. (My favourite partying shirt is 25+ years old

). But I can only party every other day now, and am anyhow more into cycling and fitness than partying when on Ibiza.
I try to do one big club on each trip, and therefore only ruin 1-2 days of cycling.
There are always a few older people at clubs, although many more in clubs on Ibiza than back home. I think this will only increase. People these days don't grow old like before. Besides, even 20 years ago the older people often seemed the happiest of all at clubs. Why stop going?
There's a Seinfeld joke about how guys peak at a certain age, and wear the exact same style of clothes the rest of their lives. I hope this is me, in the way that as I do the exact same activities when I'm 70 as I both do today and did when I was 30: surfing, mountaineering, off-piste skiing, partying/raves etc.
I'll see you guys - my fellow oldies - in the clubs, with a big smile, both in September this year and in 20 years time.