Why is everyone getting hung up about this idea that paid work is the only source of intellectual stimulation? Course it's not!
I think the whole issue is far wider than that. Intellectual stimulation is one reward of my career, but there are countless other facets - eg the travel/meeting people I get to do (and yes, I know you can travel and meet people when you are not working too, before anyone throws the obvious at me, but I meet people who I wouldnt otherwise come into contact with, and that's great). I also like the team working and management aspects of my job. And yes, the money is nice too, and although I think I would probably still want to have some kind of structured employment even if it wasnt paid, I'm not going to pretend that it's not bloody nice having someone give you a wodge of money for doing your job well. Yes, that is one aspect of feeling valued - not the only one, but important.
I wouldnt say the being paid provides the stimulation, but it's important.
At the end of the day, I think we've also got to be realistic that many of us (and this will apply to our children in turn as they reach adulthood) need to have skills and training to earn a good amount of money - because that is fundamental to having access to the choice that all of us seem to be agreed on as fundamental to fulfilment. I would be extremely concerned, for example, if one of my daughters were to decide to have a baby before getting a training and having a decent earning capacity. Of course, if it happened, I would try to support my daughter to the hilt - but I would far rather she put herself into a position to provide a good standard of living.
There are very few people who are born into money, or have exceptional circumstances where they can guarantee that a spouse/parent/ sugar daddy /whatever will pay their way for them in life. Most of us need (and actually many of us want) to pay our way.