To them, banks represent capitalism (without distinguishing between the crony and the free market varieties), to us they represent statism / cronyism. So maybe cronyism in general is the largest common denominator to attack.

I always thought of myself as being against leftism, but then I read that agorist is left-wing libertarian, because Konkin made this important distinction between cronyism and free market capitalism, and due to perhaps confusing terminology, considered himself anti-capitalist, meaning anti-cronyist.

The hardest part may be to convince the leftist that regulation serves cronyism under the pretense of protecting the people.