So as a thought experiment, yours is flawed. Because you’re not taking into account that the person buying the one month repeatedly isn’t doubling their rewards. They’re getting an “extra” 3%.
Now take into account the price difference. Nominally you get 365 days for the price of 300 with the 1 year deal. If you manage the 30 day deal perfectly (renewing within minutes) then you get an “extra” 12 days. Except… you’re still behind 53 days compared to the cheaper offer.
And, finally, let’s go back to your thought experiment, simply because it’s easier to demonstrate. If I buy VIP of any length when do I receive the rewards? Immediately only? So then what exactly is it counting down for? Absolutely nothing, AND it creates confusion and customer dissatisfaction when it expires and you get nothing. If I get them when the counter expires then there’s no immediate reward, which discourages buying and creates dissatisfaction again.
As I said in my first post they have changed this several times, and they’re back to how it works now. They’ve done the same analysis and are apparently fine with it, because those wanting that massive extra 3% a month are paying them more.