Because not buying a $1000 piece of furniture would only pay for 1-2 months of rent of a large space?

If you live in a proper city, like much of Europe, space is at a serious premium.

Although the video depicts tiny one-room apartments, the second market for this is people who'd like some extra space without the cost and inconvenience of extending their house or moving house.

i.e. if you're willing to pay $2000 to get space for a home office or exercise space, that'll get you a pretty fancy folding bed - but it's a fraction of the cost of an extra bedroom.

You don’t need something robotic but I expect folding beds (especially outside the most expensive cities) see a lot of use in guest bedrooms and similar. A traditional bed sort of locks a room into a guest bedroom function even if it’s rarely used as such. Better to have a sofa bed of some sort and use it for whatever purpose most of the time.

I think many people who can afford this sort of thing barely have any money to rent a closet in a city like Singapore.