> volunteering
Sure, I guess -- if you're not charging for your time, it's more efficient to use human labor than AI+robots.
> inventing
If we get working AI, humans will be unemployable at inventing useful things.
> teaching
There are already multiple startups trying to replace teachers in the classroom.
> If we get working AI, humans will be unemployable at inventing useful things.
The point you're responding to is that humans would be able to do it for personal fulfillment and thus preserve their mental health, not to be useful to someone else.