How would you respond if someone tried to convince you to become a nurse because "there aren't enough men in nursing"?
Women go into nursing to find doctor husbands. get more female doctors and you will attract more male nurses problem solved
But the point is the job is enjoyable because of the result and the people in it whether it be IT or construction or farming or whatever
If the people around you suck or if the job is a pain or pointless you will hate it. I get customers in both areas who want the near impossible and I have employees and contractors in both that are so stupid you are constantly looking for new ones (Shooting them while it may be more humane, is currently illegal) but then you have the others that make it worth it
It will also kill off the entire replacement parts industry. Cars, washing machines, fridges, etc, etc.
Not that I'm complaining, but it's not always an easy transition.
Not Likely however it may make it more efficient and able to produce parts for a longer time. It was explained once to me that when a manufacturer makes parts they estimate how many spares they will require for the future, manufacture them, then store them. The storage cost is incrementally added to each part hence why they are so expensive. 3D printing would go some way to eliminate the storage problem but it would not eliminate need for special materials used by the manufacturer or the precise specs which they could have in their own printing machine. Also when the last part is sold then your product is obsolete and no longer repairable with genuine parts. 3D printing could also make your product last longer in that parts would be available indefinitely.