My expectation is by the time the first colonists land on Mars, there will have been numerous autonomous missions that have setup methane and oxygen plants as well as metric tons of MRE's. That still doesn't mitigate the danger of half way to Mars your ship gets zorched by a CME. Or upon decent unbenounced to the crew a micrometeor has cracked the PICA heat shield and everybody on the surface is treated to a brilliant light show as a 100t of cargo and 100 people get sprayed across the martian sky. Without shielding in the MCT or on the colony on Mars what's your daily radiation exposure going to be? What number of people after spending 80 days weightless will land on Mars only to have their hearts give out, or that slight embolism that got stressed during take off finally pops?
I'm completely fine with risk, the question that needs to be asked is what the risk factor is going to be. Unfortunately, we can model this problem all we want, but people will still have to go do it and see what happens. I know before I'm too old of a man, they'll be a monument to the brave pioneers of colonization who gave their lives.