One votes for the same reason one extends a middle finger. It is a rude gesture towards the losing party.
Would you drive past the Nestlé factory without throwing up the impudent finger? Would you allow a cybertruck to drive past without a monodigit salute? Would you let Trump appear on your television without presenting the central phalanges? No. This is why we vote for the least shitty of 2 turdic candidates. Because fuck that other 1.