A flat rate typically implies a set percentage of income, regardless of how much you make, with no breaks or reductions.
So, a 10% flat rate on someone who only makes $30,000 is $3000, while the guy who makes $5,000,000 pays $500,000.
Ignoring the obvious flaw of throwing out the importance of infinity here, they would be exceedingly unlikely but technically not unable. A random occurrence is just as likely to happen on try number 1 as it is on try number 10 billion. It doesn't become any more or less likely as iterations occur. This is an all too common failure of understanding how probabilities work.
While this is a shit move by whoever is doing this, it makes virtually no difference for the presidential election. WA electoral votes are winner-takes-all, and always go Dem. A few burned boxes won't come close in making a difference for president, Biden won by almost a million votes in the last one. It will probably have a decent effect on local elections though.
I actually can't believe they're trying to sell that place for that much. Ritzville has literally nothing going on and it's in the middle of nowhere.