Hi heartcore.
I relate to this thread in a few ways and these are also recurring questions for me. The story of robbing your friends for $20 is indeed very upsetting. I experienced something similar several years ago, was mugged on the street by two guys who took my purse that had nothing of value for them but it was a major pain for me because it contained my passport and credit cards. It also had my apartment keys and home address, so I had to have the locks changed quickly. I doubt they benefited anything from mugging me but it was a pain for me having to call the police, canceling my credit cards, getting a new passport that took over two months... I did not feel that the incident had a strong emotional impact on me beyond the initial shock that lasted a couple hours, but in retrospect I think that was definitely not true and the mugging experience affected my feelings and attitude toward many things. I must also mention that I was mildly intoxicated when it happened and my memories are a bit fuzzy. People at work, including my supervisors, heard about my mugging incident and I was offered free counseling that would have been provided by someone at our institution. I declined it without a second thought, not even grasping why I would need that and what it might give me (it was long before I got into all my therapy adventures and learned it's something I like a lot).
I often think about the question of authenticity and what it means in different contexts. I think it's true that hiding vulnerabilities behind an emotional armor prevents us from interacting with the external world in certain meaningful ways. I definitely do a lot of that in everyday life and agree with those that brought up that certain professional environments encourage behaving that way (I am an academic). I also tend to find myself drawn to people who are very professional and that often comes with the "side effects" of concealing weaknesses and insecurities. But is this incompatible with authenticity? I personally don't think so. Does not authenticity mean being true to ourselves and our values? If so, then for someone who values professionalism and equanimity, not falling apart and getting very temperamental, it just fits with who we are. Of course too much of that and being standoffish can prevent connecting with others in a more "human" way and lead to loneliness. I also think that when we get overly absorbed in individualism and unique features, it can also become very isolating.
For me, what broke through my walls most efficiently was the very experience of active alcoholism. When becoming very vulnerable was no longer an option as it was beyond my control. The severe major depressive episode I had once while drinking heavily, which interfered with pretty much everything I valued in myself and with my tendency wanting to appear "together" at all times. It wasn't a good experience but thought me important lessons about seeking and accepting help. I did put some of my armors back in sobriety but it's significantly less than earlier in my life, and it's quite rewarding being this way. I do not behave the same way with everyone though and still find it's best to be most vulnerable and open in a select few relationships. I find that it works best with an intimate partner but also with close friends and even sometimes with a mentor I trust. Many people also go into therapy for the same reason. For me, a good therapy relationship can definitely provide some safe and open arena to explore vulnerabilities but I am only willing to go so far with that as that sort of relationship is very limited compared with real close friendships. My last therapist once pointed out something I really liked though: that having good boundaries is quite different from building walls around ourselves.
Anyhow, I personally always think that it's best to develop one or a few close connections with people we trust and relate to naturally rather than aiming to be vulnerable in broader and more superficial, less satisfying ways.