Started with 170 Marcus Semien's which I bought for anywhere from 1800-3000.
Played my risk aversion card and sold off 70 for 3900 after tax so if he doesn't get the bump I'm cutting my losses... and if he does still go diamond, I'm rich.
People buying for 4400 means their betting he has 90% chance to go diamond. And although I believe in my investments, you also have to know when to sell, to make sure I'm (a) not empty-handed if he doesn't go diamond and (b) am able to reinvest if his price plunges after not going diamond.
I think there's about a 65% chance he goes diamond (making his value 5,000 quicksell) which means that I shouldn't buy over 3,250 stubs (.6*5000). And that's about in line with what I did, only entering the market at 3100ish, but buying a majority of my supply for much cheaper in the 1800-2500 stubs range.