[Question] “New EA cause area: voting”; or, “what’s wrong with this calculation?”

Consider my home county:

  • Number of voters

  • (Corollary: probability of swinging an election: )

  • GDP: $400B

  • Amount by which GDP might go up or down depending on a single election: 0.1%

  • Probability I support the better side: 60%

Expected GDP increase from my voting
… = (fraction of GDP at stake) * P(I swing election) * (P(I’m good) - P(I’m bad))
… = ($400B * 0.1%) * (1/​800) * (60% − 40%)
… = $100k

...which seems absurdly large! And it just gets crazier as you look at larger areas, since GDP goes up like while P(swing) only goes down like . For the United States, the same calculation yields a benefit of $300k.

What’s going wrong here? (Or, is nothing going wrong? In which case, I guess I’ll stop donating to charity and devote that time and energy to Getting Out The Vote instead.)