Ventures like this cause solutions to hundreds of problems, and tech gets better. Every dollar spent on human manned exploration is priceless.
We can go to and survive on Mars: right now. If we wanted.
We need to build a massive ship in orbit, that can first go to Mars, then further. I will get behind that. But a mission whose payload is all launched from the ground can’t do it, and shouldn’t be supported.
Doing this solves dozens of problems and weight limits right away.
“Ventures like this cause solutions to hundreds of problems, and tech gets better.”
Hey, so do world wars. Is that a reason, in and of itself, to start one?
If you have to argue for your proposal based purely on possible accidental, ancillary benefits, then you might want to rethink your proposal.
Massive ships are definitely the way to go. They could carry larger crews of hundreds or thousands. The crew could be a lot less highly trained in multiple areas and be specialized in their own with multiple others similarly trained. Think of the way an aircraft carrier is crewed and run.
A ship of that size would produce a fair amount of shielding by virtue of size and amount of material alone. In times of solar flares the crew could move deeper into the ship for shelter. If you can build something of that size you can also include multiple layers of hull to help protect against small meteorite impacts.