If you buy SPS for 500 hives, you will receive, as I understand it, 5-8 SPS as a percentage, maybe I'm a little mistaken, but they will not increase the air drop.
If you staking SPTs by purchasing them today for the same amount, you will receive 4 airdrop STPs, and the interest will increase if you stake SPT coins daily. It all depends on the time, but the rate of SPS coins can overtake the profitability of buying SPS coins.
In addition, you can sell the SPT coins that you receive for curation, or increase their rate, here, some freedom of action. Buying 200K SPT you will receive curatorial rewards ranging from 200 to 550 SPT, selling them you can buy from 3-5 SPS coins, it all depends on the price of both coins, I'm talking about cheap sales. You draw conclusions)