You could also make the counterargument that older voters are wiser and have more experience and can make more sound decisions about the future of their country and should therefore have a heavier influence.
I personally think you should be able to vote on an issue in proportion to how much you care about it, but I'm not sure about the best way to go about that. One idea I've read about is to sell votes starting at $1 and the price of your next vote (you can vote as many times as you want) increases by the square of the total votes purchased (i.e. $1, $4, $9...) so that by the 100th vote you'd have to spend $10,000. But that wouldn't be a popular idea as it allows the mega rich to buy lots of votes.
I personally think you should be able to vote on an issue in proportion to how much you care about it, but I'm not sure about the best way to go about that. One idea I've read about is to sell votes starting at $1 and the price of your next vote (you can vote as many times as you want) increases by the square of the total votes purchased (i.e. $1, $4, $9...) so that by the 100th vote you'd have to spend $10,000. But that wouldn't be a popular idea as it allows the mega rich to buy lots of votes.