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It is the VALUE of the vote (not power) that varies based on the price of STEEM and the total votes cast that day (since the amount of Steem to be distributed is fixed and the number of votes are not)

Answer from @thecryptofiend
"As for why the dollar value of the vote tally varies from minute to minute it is not that complicated.
The value of each vote is dependent on how many people vote each day and the price of Steem.
This is because the amount of Steem produced each day is fixed and hence a fixed amount of this is available as payment for posts via voting.
The values are only estimates and are likely to vary over time based on the difference between the number of people actually voting and the prediction system which determines the value of the vote.
In addition to this the actually moment to moment value of Steem will also vary which will also affect the figure.
To be honest given all the variables it surprising that it does not change more often."

So if more people join the platform it is more likely that there will be more voting which affects the total payout. One thing more members joining the community should affect is the price of Steem going up, although maybe with some lag.

good question.. .

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