>>213771144 (OP)tl;dr: hubris
Miller did the first 3 Mad Max movies in like a 5 year span
then in the mid 90s he started developing Mad Max 4 which more or less like a complete outline by 1999 that was nearly 1:1 what the exact story the film ended up being by the time cameras rolled in summer 2012, but he cut all of Curiosa's backstory for time
fast forward to 2022 and he films the backstory he wrote in 1999
so from Miller's perspective the Mad Max franchise has been about Furiosa for WAY longer than it ever was about Max, hence why he thought audiences would follow him on a Max-less Mad Max movie