Surely you mean you don't update the major OS version, e.g. from Sequoia (15) to Tahoe (26)? Or do you literally mean if you start on Sequoia 15.0, you stay on

Surely you mean you don't update the major OS version, e.g. from Sequoia (15) to Tahoe (26)? Or do you literally mean if you start on Sequoia 15.0, you stay on 15.0 the entire life of the machine? The former is fairly understandable, but the latter is just insane considering the number of bugs in a x.0 release (including severe security and usability issues).