Gravity too low, too cold, weak sun, no air. Really, all Mars has is dirt, and that is corrosive. We could do much better building spinning cans to live in, out in orbit. Even Venus cloudtops would be a better place to camp than Mars.

Peanut butter reliably on the shelf certainly is a greater achievement than people on Mars would be, if we ever bother. When Elon quits hyping it, Mars will slip out of the collective consciousness.