> and still think Musk's ideas are foolish

With Musk's established track record I think it's pretty arrogant for anyone to call his ideas foolish. He has achieved things that people thought were impossible or bound to fail. You can say: “I can see this potential problem”, or “I wonder how he's going to deal with this physical limitation” or similar sorts of statements. That's feedback and analysis given with respect. Simple dismissive negativity against ideas put forward by a person who would already rank in the top 10 in the world today for technological and engineering achievement is arrogance and narrow-mindedness.