Why do professors usually avoid becoming friends with their current students, even for casual hangouts or chats during breaks?

I'm almost 70 and I never saw anyone who was obviously homeless until the late 1980's even though by that time I had already lived in Nashville and Los Angeles. Why were the homeless largely invisible in the mid 20th century?
What can I do daily to remind myself that I'm created in God's image and that my value isn’t tied to my appearance?