I have found myself in a somewhat similar position starting this year. I was already a MM flyer on United but now 99% of my travel is booked up front. I also don't feel that valued as a 1K (hoping to make GS this year with ~$40-50K in spend). With that said, there are exactly two things that keep me (mostly) tied to United:
1) My wife getting my status due to my MM. This is priceless to me when she travels alone and I can't even imagine how important it will be to me if/when she travels alone with a kid.
2) The GPUs. My sister lives in London and the ability to have her in business 75%+ of the time when she comes home to see family gets me off the hook birthday and Christmas gift crunch time.
I have a paltry CC-spend compared to you ~$20K/month but I keep most of that on a United Card that gives me the choices option which basically offsets my annual out-of-pocket for personal revenue tickets.
That's just me though. Being based in Chicago the ability to remove friction from my family's travel is worth me dealing with United. I'm 33 years old and have been in MP since I was 2 so, at this point, I also have a decent runway to probably 3MM miles if my work stays the same. The lifetime stuff that they haven't stripped away yet remains an effective carrot to keep me loyal.
All IMO, obviously.