I do genuinely believe creative people will always find a way to be creative, but that might not always be singing and touring: writing, producing, teaching, film scores etc are all ways musicians can continue to be creative within music. Then there's acting, other kinds of writing, painting, making films, graphic design etc etc
If you look at the some of the bands on this thread, those who are genuinely creative will always find some way of creating.
Then there are people who just happened to be alright singers, got a deal, had some hits and tonnes of fun, made a bit of money if they were lucky and are now sales managers in Bermondsey. And good luck to them, I'm not knocking that. It's incredibly hard to build a long-term career in music and one of the skills is knowing when to call it a day (ie when you are still making money, as opposed to running up debts).
To look at an entirely different band - I think JLS were really well advised. Couple of big albums, one massive one, some tours where they (hopefully) made some cash, then the minute it started to dip they retired, married The Saturdays and will now go on to have other careers where they can live a relatively normal, stable life. Good luck to them.