I don't think thats largely the case here. Otherwise you would be able to reason with such people, which is definitely not the case here. I'd go with that extreme emotional attachment and some form of autism / other disorder.

Lets not forget non-trivial part of population is on spectrum of one/multiple psychiatric disorders, but say 2 out of 10 doesn't get you to mental asylum, rather on lifelong medicines if you get diagnosed properly, but most people do not get that luxury. So they often end up a massive pain in the A for basically everybody around them.