Sure it's per month.
Which means China could afford to do it for 64 months out of every 12. At just the amount they were spending 2 years ago- and they've increased spending massively year over year.
Not to mention what Russia has spent, which is allegedly much higher each year.
Plus, of course, as BitJam notes, unless a LARGE percentage of users go blue checkmark, the bots will happily keep pounding away with tons of free accounts too
(I mean, really, even if more than half of real users go blue checkmark, they'll STILL pound away with free bots, because the marginal cost of them is nearly zero)