Yours is a somewhat more cynical way of writing it down, but the underlying mindset is one I share.
I prefer to see it as not expecting anything from anyone, rather than expecting them to disappoint you. It’s basically the same, but doesn’t feel as cynical.
It truly changes your life though, no matter how you see it. I can’t remember myself having been, in real life, angry or disappointed in people in great many years. Life is just so much better without those feelings, which seems obvious, but you can’t really emphasis that enough still.
It took me years of self-reflecting and “finding myself” in the process of overcoming a years-long bout of clinical depression. It’s not easy, but I do believe everyone can find that mindset, given enough effort and perseverance. Sisu.