I have a city built on the peak of a 3 km-high mountain that moves from place to place on a daily basis, the whole mountain appearing in a new place each dawn. Typically, the place in which it appears is or has experienced winter conditions, or at least colder conditions than usual.
The city survives by trading with people who live in the places it appears - these places trade goods such as foodstuffs, timber and other raw materials for magical or technological items that are produced on the city, or for services provided in the city. The city's technological level is similar to renaissance Europe, and the magic is similar to that depicted in the Ars Magica RPGs, though with much less restraint of trade as imposed by that RPG's Order of Hermes.
I have people who are interested in setting up at two or three new businesses in this city, and who are looking for businesses that have closed down or are no longer prospering so that they can make an offer for the properties. They are looking in the middle-class to upper-class areas (not coincidentally also the mid to upper levels of the city), so the businesses that they are looking to displace must once have been moderately to highly profitable.
What sorts of businesses could initially prosper but ultimately fail in such an environment, and for what reasons?