Well not sure what you mean by 'Conman'. Wildly successful people do aim high a lot, a lot. They don't meet 80% of their goals, that is perfectly ok. Even as low as 20% success on a lot of these moonshot things sets you ahead of the masses who aim very low and get there 100% of the times.
This whole idea that some one has to comply to your idea of how one must set goals, and get there is something other people have no obligations to measure up to. Also that's the deal about his lies? He can say whatever he wants, and not get there. He is not exactly holding an oath to you or any one that he is at an error for not measuring up.
Musk might not get to Mars, he might end up mining asteroids or something. That is ok. That doesn't make him a conman.
tl;dr. Any one can say, work and fail at anything they want. And they don't owe anybody an explanation for a darn thing.
This whole idea that some one has to comply to your idea of how one must set goals, and get there is something other people have no obligations to measure up to. Also that's the deal about his lies? He can say whatever he wants, and not get there. He is not exactly holding an oath to you or any one that he is at an error for not measuring up.
Musk might not get to Mars, he might end up mining asteroids or something. That is ok. That doesn't make him a conman.
tl;dr. Any one can say, work and fail at anything they want. And they don't owe anybody an explanation for a darn thing.