Trump isn't necessarily going after "the worst", he's going after biggest, most visible targets. Consider the list: NYC is a front and center example of a city bleeding out people. Washington D.C. is almost in open rebellion to the Feds with what they are trying with the monuments. Seattle had the CHAZ. Portland's mayor is attacking Trump and simultaneously failing his city on the national stage. All of these cities repeatedly refused Federal assistance.

Trump is fighting on the national stage and taking on the most visible targets for maximum visual effect to showcase consequences.