What is it that people can do on Mars so much better than robots that it is worth spending 1000 x the money on putting people on Mars.
People spend most of the time in space trying not to die.
Most of the spaceship resources are devoted to people not dying.
When they are not "not dying" they also need to eat, sleep and poo. Being living organisms (for now), people contaminate the planet with all of their germs and fellow travellers.
You get very little useful activity out of people before they die. Mostly they will be using sensors to analyse Mars.
Advanced robotic missions can do 1000x the science for 1/1000 the cost. If you need people to look at sensor output, put them on planet Earth where oxygen is widely available.
You can create swarms of robots that can scout, direct, maintain, repair and recover each other. They can be active for ling periods without rest. If they need downtime, there is rarely a critical time factor.
What are people for except to be role models.
The only fantasy reason is for some kind of population lifeboat for when Earth gets hit by an asteroid, then Dr Stangemusk and several hundred highly qualified yet striking attractive fertile young women will be on tap to save humanity.