You can hope to do something about "how stupid people are", but only in the long term.

In the immediate term, where the election is tomorrow, Recognising that it is only a small contribution towards staving off disaster, and acting to make other choices possible is far more important; Disliking both intensely for their corruption and self-serving bias; Holding your nose so hard it turns blue, vote B, vote B, please vote B.

(edited following parent edit)