No, I've really never heard of this guy until the flamethrower thing.
invented paypal, sold it, went on to create solarcity, tesla motors, spacex, and "the boring company" among other things
genuinely cool dude but the reddit-esque Dude... Science!!!! types worship him like he invented electricity
definitely a PR move to launch the car but this mission isnt just memes; to my knowledge spaceX has never launched a mars mission, so this'll be something of a test run. the car's just a placeholder weight