Surely you're playing hyberole? The machines were pretty well marketed and most universities had them. I knew people who had one. And as a teenager, I wished I had the cash to get them, used to play with them at my sister's university bookstore.
McGill University in Montreal had an undergraduate computing lab full of NeXT machines in the early 1990s. Visiting the lab was the high point of the tour they gave to prospective students.
To put more flesh on the bone, there were apparently about 40,000 NeXT users in 1993, many highly loyal. https://books.google.ie/books?id=QDsEAAAAMBAJ&pg=PA54&lpg=PA... So while the NeXT system certainly wasn't a mass-market hit and the company struggled financially, it wasn't quite as quirky and deeply obscure as it may seem nowadays.
However, nobody really ever got to see a NeXT machine apart from Tim Berners Lee. The web really was 'next' so it all worked out well in the end.