Where did you find that paying customers have 100 users on average? In that case it would also only be 30,000 customers * 100 users * 10 = $30M a year.
However, you're missing that the price is $9.99/month/user, not per year (for some reason I used $11.99, which is the price when not billed annually).
So it's 30,000 customers * 100 users * 9.99 * 12 ~= $360m per year. Your $30m is per month.