Betting on the 2020 US presidential election *after* the election

A couple weeks after the 2020 US presidential election was held, Nate Silver tweeted several times about the irrationality of betting markets (for example PredictIt), since they still had a 10% chance of Trump wining various states.

Other versions of this tweet talked about "free money" and "money left on the table".  I decided to try it out for myself discovering along the way that Nate failed to take into account transaction costs and market limits/barriers that contribute substantially to maker distortion.  In other words, it's not solely as Nate says irrational people, but also other well know sources of market inefficiencies..

TL;DR I made a net profit of 6.8% in 1.3 months (before taxes, ~4.5% after taxes), from a gross profit of 13.8%.  The 13.8% is close to (slightly higher than) the headline-grabbing number about irrational people in the markets, but from this example you can see that 67% of that "irrationality" is wiped out by simple transaction fees. 

Here's a brief timeline of what I did, and how I discovered on the fly the transaction costs.  Yes, I know:  if I had RTFM beforehand... bold italics indicate transaction costs/barriers encountered.

1. transferred in X dollars as investment to PredictIt (11/11/2020)
2. Attempted to bet on most profitable markets - Georgia, Pennsylvania, Michigan - blocked because market had reached maximum number of traders
3. Invested in next most profitable market (Arizona) - hit maximum allowed investment (Y)
4. Repeated by investing in next most profitable markets (Wisconsin, Nevada)
5. Later, Georgia market opened up, invested smaller remaining amount (~Y/2)
6. Most of these markets closed around December 15, 2020, 
1. NB:  however PredictIt delayed Wisconsin b/c of a Wisconsin Supreme Court Ruling
7. Overall gross profit was 13.8%
8. PredictIt takes 10% of winnings, so percent winnings was 12.4%
9. Withdrew all money (12/21/2020), PredictIt takes 5% of all money withdrawn, so profit in hand is 6.8%
10. I'm going to pay income taxes (around 33%) on the winnings, which makes profit after income tax 4.5%

Although it all worked out in the end, during the entire time my money was invested I was worried about the possibility of losing it all.  Perhaps this was unrealistic, but given the crazy political and social atmosphere it was hard to avoid feeling that way.