The hoverboards are for kids as far as I can tell. Childhood just isn't the same without some way to bust your face open. Parks got nerfed by a well-meaning child safety crusade that fixed nothing and ruined playgrounds; because the problem wasn't that the playgrounds are dangerous - the problem was that kids are stupid and clumsy so sometimes shit happens and a kid will die tragically. It's literally unavailable, that's what makes it an accident.
Some of these kinds of things - especially "as seen in tv" stuff advertised by fumblebums - are actually intended for people who are partially or wholly physically disabled. But if they market it for disabled people then they'll sell less of them and the price will go up, and because we live in America hell, the disabled didn't make nearly enough to survive as is. So they market it to everybody with an over-the-top ad instead. Remember the Snuggy? Literally designed for people in wheelchairs and with mobility issues.
The rest is just brand awareness bullshit and market expansion. Seriously, man-wipes exist because they'd hit market saturation and are trying to squeeze out a profit increase by targeting a different demographic. Because in capitalism, the line MUST go up. Brand awareness is just a way of saying "Hey! Pay attention to me, I'm Diet Coke! Don't forget! Are you thirsty now? Pick me!" And the quest part? Both stupid trucks work because people are dumb.
Some of these kinds of things [...] are actually intended for people who are partially or wholly physically disabled.
After I learned this, I immediately felt bad for poking fun at these kinds of products. Normalizing their use by the non-disabled, and depicting the products likewise on TV, makes it that much more acceptable to the intended audience. If this wasn't the case, it might sting a bit as a gift for someone that really needs it. And then there's the economy of scale effect you mention; nobody would get a Snuggy if they cost $100 each.