The vulnerability that you are describing does not affect all implementations of democracy. For example, most countries give out the right to vote based on bir

The vulnerability that you are describing does not affect all implementations of democracy. For example, most countries give out the right to vote based on birth or upon completion of paperwork. It is possible to game that system, by just making more people, or rushing people through the paperwork. Another implementation of democracy treats voting rights as assets. This is how public corporations work. 1 share, 1 vote. The world can change endlessly around that system, and the vote cannot be gamed. If you want more votes, then you have to buy them fair and square.