Using a very rough ballpark estimate, it costs $1 / month to run a twitter bot using readily available technology, see, for example, https://jarvee.com/get-now pricing list. To think that for $50k / month anyone in the world can have a [significant?] impact on US elections is bizarre.
In practice, there is a negligible probability that posting a tweet from a random bot will end up in the feeds for a target demographic. The feed space of the 80k people WP claims decide the election is finite, and it costs significantly more money to reach them than setting up small scale botnets. Ultimately, Twitter is in control of the feeds, and it's their business model to happily direct any message from the highest bidder to the critical demographic, regardless of who or where the highest bidder is.
In practice, there is a negligible probability that posting a tweet from a random bot will end up in the feeds for a target demographic. The feed space of the 80k people WP claims decide the election is finite, and it costs significantly more money to reach them than setting up small scale botnets. Ultimately, Twitter is in control of the feeds, and it's their business model to happily direct any message from the highest bidder to the critical demographic, regardless of who or where the highest bidder is.