I think the key phrase in your post, Warwick, is "the wish to perform". To me, this implies that the performer is centered on self, rather than on the audience.

Unfortunately,the wish to perform doesn't automatically confer the right to be heard.

As for people in their seventies - well, I'm one of them, and happy to perform for 2-3 hours off the cuff, which I do regularly. I wouldn't in a million years claim to be the greatest performer in the world - or even in my village - but I've worked hard over 50 years or so to try and give people pleasure and earn a few bob now and then. Which has been very enjoyable for me and, I hope, for the audiences I've played to. (I've also had a full life!)

Of course none of us is perfect - we all stumble occasionally - but good preparation minimises this, and the work put in reaps its own reward when you get to be "at one" with the audience.