If you have never had to pay rent, health insurance, utilities, and don't know what it's like to meet the basic requirements to survive on your own, and you are under 21, you should not have the entitlement to make choices that impact all that do pay their rent. Why should a teenager that is not functioning in the real world get to decide what the government is going to do to YOU?
We send our 18 year olds to college. Why? Because the don't have enough education yet. So why are we allowing them to vote on something that really requires knowledge?
What makes the number 18 so special?
Of course there should be exceptions. If you are 18 and are in the Armed
Services, yes, you get to vote. If you are 18 and and can provide an
electrical bill in your own name and show you are not a dependent, then
you get a voter card giving you access to the voting booth.
The exceptions can be hashed out.
However, if the adults of the U.S. continue to allow an ignorant, Lord of the Flies contingent to
influence the fate of this country, then they have abdicated their
responsibility as adults. And both the young, and the old, will face the
consequences.

Amendment XXVI was passed on an emotional Vietnam war slogan, "Old enough to fight, old enough to vote"...That should be the exception, not the rule.
The democrats now want 16 year olds to vote because they pay taxes. Well, what about the 15 or 14 year olds pay taxes? If that's the criteria, anyone that pays taxes should be allowed to vote. Which begs the question, should foreigners that pay taxes be allowed to vote? And should American citizens that do not pay taxes be barred from voting? Obviously, tax paying cannot be the sole criteria. How much skin you have in the game should be the main criteria. If you are independent, paying most or all your bills and are not a tax dependent on your parents or guardian, then you should vote.
The majority of 18-24 year olds live at home. So, for the sake of this country, let's split the difference and keep it at 21.
~Dhruva Aliman