He's a bullshitter (cf hyperloop) and a fraud (cf SolarCity fake solar panels).
His initial plan for hyperloop is a ~200yo design[1], only he enhanced it by putting "a air-hockey table" (his words) inside an evacuated tube. How stupid can one be?
He assembled an audience on a film studio set with mansions to show off non-existent solar shingles. He's well known to have been promising fully self-driving cars as well as flying rockets to the Moon and Mars year after year after year, always adding he was "confident" to accomplish that by "this_year + n" where n < 6 for "1/x th of the current market price" where x is typically 10 or 100.
[1](https://spectrum.ieee.org/hyperloop-is-hyper-old): ""Lord how this world improves as we grow older," reads the caption for a panel in the "March of Intellect," part of a series of colored etchings published between 1825 and 1829. The artist, William Heath (1794–1840), shows many futuristic contraptions, including a four-wheeled steam-powered horse called Velocity, a suspension bridge from Cape Town to Bengal, a gun-carrying platform lifted by four balloons, and a giant winged flying fish conveying convicts from England to New South Wales, in Australia. But the main object is a massive, seamless metallic tube taking travelers from East London's Greenwich Hill to Bengal, courtesy of the Grand Vacuum Tube Company."