The sort of person who becomes an exceptional scientist, or generally the sort of person who excels at any mental activity, is also generally the sort of person

The sort of person who becomes an exceptional scientist, or generally the sort of person who excels at any mental activity, is also generally the sort of person who does not get bored. Beyond that, their schedules will be jam packed. They're going to be spending hours per day exercising, hours in diagnostics and maintenance, hours in training, hours in general work (pathing, communications, logging, running experiments, etc) and then hopefully getting an hour or two to themselves at some point before doing it all over again the next day. And that's before they even get to Mars, which is when the real work begins. When you're tens of millions of miles away from Earth there are countless things that can go wrong, and a good chunk of them end up with everybody dying. By contrast there are very few paths to a completely successful mission, and maximizing the chances for that is going to entail an enormous amount of work and energy.