My well off family has one of those. And yes it was addiction related. No one wanted to admit there was a problem so it dragged on for a decade. After learning the hard way all I could do was decline mooch attempts and not argue about the mess with family.

Odd related story. I was acquainted with a couple in their 30s whose livelihood was mooching. They took turns hitting up extended family and kept track as to who they had leeched from on a rotation list. Not stoners, just a couple of smart but flaky collage dropouts. They were very frugal. The long term plan was to hope for an inheritance. Don't know whatever happened to them, can't recall their last name anymore.