Why do you think they picked up the $250 k figure?

Because most of the senators makes in that range from uncle sam and their other income, investments , holdings etc is technically hidden in the so-called Blind trust, this way they can hide and shield their investments from public viewing and from the Political filings they are required to file every year.

IMO they want to go after the 1% of wealthy americans that make a lot of $$ like actors actresses sports figures, tv personalities etc. etc.

JMHO