Your insistence on using the Hope BB and Einstein’s definition of insanity aren’t to dissimilar 😁.
You might not be getting the preload right, might be worth seeing how others adjust theirs to compare, for example, how freely should the cranks spin without pedals on, how many revolutions should the cranks spin before coming to a stop.

I’m about to junk my 3rd set of GX cranks in 4 years because of axle wear.

I like GX – they are nice and stiff and acceptably light, but the failure mode on the axle when the bearings seize leaves you no way back because its a soft alu, and despite the correct torque on the crank bolt, its pretty easy to turn the cranks against the plastic spacer of the bearing instead of the bearing. Even a free running dub BB isn’t exactly ‘spinny’ to start with so it can be difficult to tell.

It’s not their fault specifically, but you only have to ‘not notice’ once and the axle is done, so the design isn’t very tolerant of wear/damage when the whole thing is functioning sub-optimally.

I think the root cause is the dub BB design and is 2 fold. The support of the bearing in the cup is pretty minimal where it ties to the threaded section and results in unavoidable flex and moisture ingress from flexed/insufficient seals.

Interestingly, I have no such issues with the dub crank using a hope BB on my summer bike.

I’m shifting back to Shimano with their steel, nickel plated axles for the sake of a bit of resilience if/when it happens again. I still have a set of 2003 HT2 cranks running on my daughters bike. Presently, Shimano BSA Bbs can also be got for half the price of a dub BB. So running cost should be lower too.