The chance of having a real progressive (yes, she is, and if you disagree you're a clown) with a track record of holding corporate ghouls to account serving in the Senate for the next 30+ years is absolutely worth diverting a bit more money. Also a D vs D Senate race will depress Republican turnout and help Dems downballot too.
This logic only really applies in a midterm year. Republicans are gonna turn out to vote for Trump regardless of the senate race's outcome look at 2016. The Harris vs Sanchez race had no effect on turnout statewide. Anyway im proud to have voted for Lee, though if Porter makes the runoff against Schiff ill vote for her.