Overall billionaires wasting their money to pay for idiots that then waste it in consumption would be a tax positive, I believe. We should encourage that behavior instead of them buying assets and then extracting rents like the parasites they are. I don’t care if they get to write off the money they lose from their income.
Most of them would be denatured by stomach acidity but the risk of something like paradoxin finding a small route into your blood stream is too damn high.
When it comes to venom that is also used as a toxin in other species, though, and is a big killer of humans, the crown goes to https://en.m.wikipedia.org/wiki/Tetrodotoxin which is used as both a poison against predators for things like pufferfish and a venom for things like the blue ringed octopus.