Probably several real reasons… and i think he just throws shit at the wall until he finds something that sticks but this one stuck because among his followers it ticks several boxes…
He already did a dry run in Los Angeles, literally chasing harmless day laborers through Home Depot parking lots. Newsom (Cali Gov) made it more difficult by trolling him on social media. (I realize how insane that sounds but he just has the temperament of a teenage boy). So he is probably thinking of something even more insane to do to us in Cali or at least knows he’s playing with fire.
New York he is lowkey working on a deal with Cuomo (former mayor now running as a spoiler candidate to the socialist who beat him in the primary election).
Chicago is an easier target. The only other city I’ve heard him float is New Orleans (which is unlike any other city I’ve been to in the states for its amazing seafood, bars, walkable areas, music, eg culture… notably Black culture)
His mostly rural base loves it. Not only is it cities that they have been other-ing and blaming [insert South Park - They took 'er jobs meme] for their problems their whole lives. It is also abuse of minorities. So it is like saying “you know how you complain about cities and they happen to be brown and black. Im going to fix that problem and it just so happens to be by going after those people who don’t look like you. wink wink, nudge nudge”
DJT Jr 2028-2036
Ivanka 2036-2044
Baron 2044-Apoclypse