Has it all been worth it?

Other than pissing away money on cables, I think the upgrades that I've made have been worth it.  I listen to music for a couple of hours every night. I've got other hobbies that don't produce the satisfaction that I get from listening to music. 

I do, however, feel that I'm at a stopping point.  I'm happy where I'm at and don't feel like investing any more money to get that tiny bit of improvement. 

You didn't mention 8 track tapes.  Surely, you didn't skip those.  I didn't.  :)

Once I heard an 8 track I never looked at them seriously. 

I think it has been. I've been on this Merry-Go-Round for only about 25 years, so a lot less than many people here. But an important point to remember is that this hobby is for a very select few for whom auditory satisfaction is a source of contentment. We're also Gearheads to an extent and we just like tinkering with things. We get an aural pleasure that the vast majority of people don't really care about and find elsewhere. Having said that, as I've posted earlier, I restored, refinished, and rebuilt a very old pair of coral speakers several months ago and only the other night did I finally take them off my listening stands and put my reference 3A's back up. I just would have been very happy with these essentially free speakers as opposed to much more substantial (and more resolving and clear) De Capos. 

death is the only offramp and then….. ?

It has been in my case. The end result has well exceeded the endless search for the best sound to my ears in the best possible listening environment. It's obviously not for everyone. The commitment has to be real to get there. It's a great way to spend my time in retirement. I never gave it that much time and attention during my working life and the quality of my systems then would speak to that.