Don't spit your coffee when you see other votes worth 20$ and more ;-)
The value of an individual vote is dependend on the market cap of steem, one's steem power, and the amount of votes cast by others.
To get a lot of steem power and make them worth more, you need to invest or work hard on earning it. The early adopters had a head start, because they invested when steem was literally worth nothing. That risk is rewarded now.
Not long ago, each vote was worth a lot more although the market cap was way lower. As the platform grows, individual votes will become worth less and less.