What sacrifice. An astronaut going to Mars in his twenties is very likely to survive quite some time. All high risk efforts will be done by robots, break one, use a spare and another is sent from earth. Sure most travel will be one way but new specialists could be sent as necessary ie damage the spine a volunteer neurologists gets some extra space training and off they go.
So the logistics chain needs to be established. From the Earth to the moon base and from that base to Mars (additional manufacture and resourcing being carried out on the moon).
To be safe is not about being able to come back, it is about how quickly resources and required staffing can be dispatched and arrive. The drive is not to get to Mars but to build a full fledged moon base housing thousands, to enable the rest of the system to be reached from an atmosphere free, low gravity environment, the moon is key for access to the rest of the solar system and the ability to make monthly launches from the moon to Mars. Not rockets but fired at Mars by a large steam cannon, still need engines to slow down, dependant upon time to Mars, quicker trip, much larger engines to slow down (those engines could make a slow trip back though).
So the problem is all about how to shift tons and tons of stuff around the solar system as fast and safely as possible. From there the rest of the galaxy. There is no way faster than gravity tests can be conducted on the earth's surface or even near it (think return trip, aim at the moon, whoops, large crater, better that crater on the moon than on the earth). You need to conquer the system to reach out to the rest of the galaxy. Major Moon base is key.