You make some valid points and I agree with you to a point. However, you have no idea what frame of reference other people may be viewing the same "evidence" through, anecdotal though it may be. Assuming the details described by the OP are true, I stand by my mental illness assessment, crystal ball and all.
What's heartbreaking is personalities like this may seem like they're "winning" and they may even revel in their victories. What's underneath is very, very sad and very, very fearful. At some level they don't want to be like they are, yet they don't have any idea how to get out and are absolutely terrified to even try, which is a vicious cycle.
It's a good reminder to all of us as parents to do a frequent gut check & honestly look at what we're doing raising our kids. Natural instinct is to want to protect, provide and assist -- help them get to the top & win. It's so important that we remember to step back, let them do the climbing, encourage them to keep striving for their wins and let them take a few tumbles so they learn they are capable of getting back on their feet themselves. Easy to say, almost impossible to do sometimes.