Personally, I wouldn’t put any money into the competition unless you were prepared to lose it all. Numerai may not succeed in their mission and then NMR could be worthless. I imagine many of the stakers with ‘big money’ in the game purchased their NMR when it cost a lot less or were given them free in an airdrop. Or maybe they just have a bigger appetite for risk…
Eventually, payouts will drop because of the planned payout decrease and I believe the long-term plan is for Numerai to buy-back NMR from the open market, using profits from the fund, to pay competitors - this adds tangible value to the token.