Walking radical wrapping the bottom-left - the indexing radical. Marks 迷 as a verb of motion gone astray: to walk and lose one's way. The 'fascination, fan' senses extend metaphorically - to lose oneself in something. Same radical anchors 进, 远, 近, 边.
Inner 米 supplies the sound: mǐ to mí, only a tone shift. Pure phonetic loan; the rice-grain meaning doesn't carry into 迷. The folk-mnemonic 'lost among the rice paddies' is a useful memory hook for learners but isn't the historical etymology.
