Your math is off. It would take 8.5 million people donating $5 a month, to equal the 510 million a year from Google.
My math (please correct me if I am wrong):
$510 million / 1 year
$ X / 1 month?
$510 million / 12 months = $42.5 million / 1 month
$42.5 million / $5 per person a month = 8.5 million people a month
Fuck that