I was 101% in when I was in. I went through a period where I faded pretty gradually, still telling myself it was the truth but my subconscious mind had already checked out. By the time I realized I was out, it wasn't traumatic. I was in for 30-40 years or so, made it to MS with people sure that I'd be an elder in due time. I'm sure there are a lot of people who feel that I wasted a lot of potential.
I do feel a bit of sadness for losing out on some possible career paths that I decided not to follow, but I got lucky- an opportunity in IT when I was just beginning to fade allowed me to develop a career and make a decent living. My life was in good shape when I finally let go and walked away from the org. No bitterness, no looking back.