Holding Splinterlands assets awards points towards the airdrop. SPT has an airdrop points value of 0.25. The below link will take you to the section of the whitepaper that shows the points value of different Splinterlands assets.
https://sps.splinterlands.com/airdrop

I agree SPT USD value is insanely low making the upside of buying up a whales share very tempting. SPT has allot of tokens given out per topic. If you take a look at its front end, Splintertalk.io, the trending topics earn 10,000 + SPT. That's allot of token to be attaining per topic when the 24 hour sales volume of such a topic struggles to reach $10 USD. Too many tokens being given out and no use case leaves everyone holding a bunch of SPT that they have nothing to do with but sell for cheap. Hopefully an ongoing use case gets introduce at some point so those of use who have been holding and buying up the cheap SPT can enjoy the mooning.