[throw3823423]

The idea of making fuel on Mars was popular enough to have the calculations be part of undergraduate thesis' over 20 years ago, back when I was in college. I bet that people far more serious than Aerospace Engineering undergrads have been coming up with far more detailed versions decades before that. But those plans are no panacea: The fuel creation takes time, so you are either sending a mission first, just to make fuel, hoping it all goes well, and then send a second mission later, or you might end up having to keep your rocket in the surface of mars in good shape, still able to come back, for quite a bit. You also have to consider general timing: It's not as if efficient trips in either direction can be done any random day, of any random year, just due to orbits.

So yes, the mars fueling idea is compelling, but let's not assume that the people doing this for a living, and proposing this plan, are just worse at this than random undergrads.