Um, since at least 1970 with arrival of the Koss 4As.[1] And these were followed up by similar classics such as the AKG K240s from the early 1980s as well as the Grado SR80Es or Sony MDR7506s from the early 90s.[2][3][4]. However there are many more.
There is quite an active market for these and they are highly sought after because of their audiophile and build quality. Anyone who was fortunate enough to have inherited them likely for those reasons.
[1] https://www.koss.com/history
[2] https://overearmania.com/2019/01/19/akg-k240-monitor/