After reading this thing through, it seems the only thing that’s driving the Russian billionaire to proposing this improbable fantasy of his is the impending close proximity of Earth and Mars. He keeps on talking about this small window of opportunity that would make the trip to Mars viable because of the relatively lesser resources a trip at this junction would require, mostly in the inability of the human condition to tolerate extended periods in space. At any other time, the Earth-Mars positioning would not be conducive to such an undertaking.
That window comes every year.
Going to mars and back cheaply would involve about 5 or more launches. With each launch using a gravitational sling shot manuever between the earth and moon.
The first launch would put the return vehicle in mars orbit with food and fuel for the return.
The second would be fuel tanks, also in mars orbit.
Then you need a bigger, LEM like vehicle on the ground.
then you put the food and fuel for the outgoing mission into earth orbit.
The last thing you do is to put the astronauts on the way to mars.
You do this to use a smaller launch rocket which is cheaper.
Plus with a bigger payload you need more fuel, and then you need some more fuel to lift the fuel and even more fuel that lifts the fuel that lifts the fuel.
Many launches with small payloads and using a slingshot is the way to go.
But that means a very complicated and drawn out process with more things that can go wrong.