There are numerous nasayers who point out the challenges of a mars trip.

But all of the challenges are known and can be mitigated. The biggies...

Overall duration and space exposure: advanced propulsion systems can get there *much* faster. Or just send fuel tankers so you can run the engines more.

Radiation: Shielding. Submarine crews actually get less exposure submerged than sitting home in their living rooms, despite being a few feet from a reactor producing power levels measured in large numbers of megawatts. Need to get creative to save weight, but lead isn't the only suitable shielding (layers of various materials actually work better anyway).

Gravity: Any four year old on a playground knows intuitively how "artificial" gravity works. And you wouldn't actually need 1G... 0.3-0.4G (Mars local) would work fine. We already know how to recover astronauts back to earth after lengthy ISS stays, the trick on this mission is being able to function on arrival at Mars without length rehab.

Really it all comes to down to money.