This guy beat 'em to the punch years ago, but I think he kinda gave up when he realized he didn't have the power-to-weight to break ground effect. Your guys, on the other hand, said 'ground effect? who cares, it's a hover bike!' and started marketing. Thing of it is, the X-jet was way cooler in 1967: Basic problem is the motor: Williams International was developing the F107 for the ALCM and Tomahawk cruise missiles and sorta went "what the heck! Let's build a skateboard out of it!" but the thrust is just barely enough for a skinny guy and some gas. And while Williams has hardly been resting on its laurels, their advancements have been more about fuel efficiency than greater thrust. And let's be honest: your average rich yuppie isn't in a position to buy two $160k turbofans. And if you had one, there are other, sillier things to do with it.