This along with Saver is not accumulative as the descriptions would suggest rather you need to be holding 500,000 thousand lucre at once for it to unlock. Good news is it all carries over across NG+ and since you need to do 3 playthroughs anyway these achievements will come in due time!
Don't forget to sell items and gear you no longer use and if you really can't wait and are close enough you can always save, sell EVERYTHING then reload your save after popping the achievement
If you end up skipping a lot of fights during your 2nd & 3rd playthrough farming might end up being necessary and in that case the best place to do so is the post game bonus dungeon
using incense. Helpful farming video below