Ultrasonic knives have been available for non-food uses for a long time. They are useful in certain narrow applications, such as cutting leather or some plastics.

That said, they come with two big caveats. First, if you push them into any harder material, the edge is destroyed almost immediately because of the micro-scale "jackhammer" action. So, hit that avocado pit and the knife is probably cooked.

Second, the constant motion heats up the blade, to the point of melting thermoplastics or causing the edge to lose temper if you're pushing a bit too hard, cutting the wrong material, etc.

It's your money, but I suspect this knife is more of a hassle, and requires more care, than a regular kitchen knife. And let's face it, the coolness factor aside, how often do you struggle to cut chicken, tomatoes, or bread? If you do, it's probably because your knife is dull, and this knife will get dull too.