From my own impression as a member of a small political party in my own country who joined not out of tribalism but simply because they seemed to mostly want the same things as I do, party members live in a bubble of people who are heavilly into politics and understand the importance of politics, whilst the leadership specifically in addition to this are also mostly surrounded by generally unquestioningly hero worship from the common party members plus they tend to have quite limited life experience outside the party as they’ve joined it as young adults (maybe when they were at university and involved in student movements) and it and its internal environment have always been a large part of their lives.

Those people usually see the supporters of their political adversaries in the same way as fans of a sports club see fans of other clubs, and don’t really “get” the point of view of people who don’t vote at all.