> is 3-9 months depending on how fast you travel

That particular launch window only occurs once every two years. The Earth and Mars rotate around the Sun at different rates. During some periods Mars is on the other side of the Sun and essentially unreachable with our current level of delta-v.

> latest optimistic prediction

Will that be before or after fully self driving cars? Or electric semis? That drive themselves in road trains? Will those astronauts have neuralink chips in their heads?

> re-adapting to gravity on arrival will be an issue.

It's 1/3 gravity. Then again, you're on a ship with no free return abort trajectory available, I'd worry more about medical emergencies, crew temperament, and actual crimes being committed.