That isn't a natural right. That is born out of the system of governance that we've decided is best. There is no natural right to vote — not in the same way we have a natural right to speech or defense or anything else of that manner.

Democracy is dangerous. Our founding fathers despised true democracies, which is why they founded this country as a Constitutional Republic, and notably one that not everyone could vote. Many call them racist and sexist, and no doubt that was part of it, but they also understood that having a bunch of uneducated people voting could be disastrous. NO ONE should be allowed to vote your natural rights away, yet you see this in democracies all the time. You're right, though, the trick is figuring out an acceptable way to proof voting privileges.

Even the word "democracy" didn't come into popular use until the progressive era.

So yes, when we follow true Constitutionalism, voting is important because we should be selecting our leaders to uphold that limited government. But in our current system, we've given government so much power that we allow people to elect leaders that are going to give them the most, all whilst selling off the power they have taken from us to companies that want to protect their business model.

And once again, you really need to stop doing the whole, "I'm surprised you aren't smarter" bit.