Space ventures are seldom decided by reason. Going to Mars is akin to going to the moon before America was discovered. Luna must first be exploited, then comes the rest of the solar system. Forget about visiting other stars, it cannot be done. The tyranny of rockets rules all space exploration. The average solar system exploring human-staffed spacecraft that leaves from the Earth will use 99% of its volume just to fling the equipment needed to explore Mars. If, however, such a venture was launched from the moon it would be able to delivery a payload to Mars and back with less than a 50% payload to boost ratio. Eventually the only thing we should be delivering into space from the Earth is humans and high-tech gear.
Mars is the wrong step at this point in our deveolopment of space travel.
There is so much that could be done and needs to be done on the moon. The moon need to be the launch site for a trip to Mars
Our current chemical rockets are the flintlock muskets of space travel we need to move the more advanced method of propulsion before we attempt a Mars landing. To send humans to Mars with no assuured chance of return is murder.
Getting to Mars is 6 times easier from the Moon, not counting any of the other economies of scale that comes from launching from the Moon.