Seven (7) layers of seasoning that is just scrubbing right off

Wish I had a picture of the pan before I tried cooking with it but oh well.

Idk what happened. I’ve seasoned cast iron before with decent results but went above and beyond this time and really wanted this pan to be as slick and nonstick as possible. Grapeseed oil on, then wiped off, in the oven at 450, pull it out after 10-15 minutes to wipe off any excess oil, total time in oven at least 1 hour. Super thin layer of oil. SEVEN iterations of this. I thought I was solid.

Then I cooked an egg in it and it stuck to the pan. Well that was disappointing. I figured oh well, I’ll just keep cooking with it and hopefully it will get better over time.

I later on washed the pan with just water and a sponge to get the hard egg off and the seasoning just SCRUBBED RIGHT OFF, as you can see by the silver underneath. What the hell?

Now, the one big thing I did different this time was I sanded down the pan with sandpaper to try to get a smoother finish. I didn’t go crazy with it and end up with stainless steel level smooth but it was at least smoother than the factory base you get with Lodge pans. This is why the seasoning came out looking bronze instead of black, but I thought this was normal. Apparently this was a huge mistake? I just don’t understand why though when it’s worked perfectly fine for others. I’m stumped.