"I'm quite tempted to just give up on this whole thing. It looks like the site is simply at nakowa's mercy. He's promised me in the past that he won't play any more, but never sticks to his word. So what do I do? Continue to let the investors take these horrific losses?"
Well, that's a two edged thing... When U+Investors are in profit, I'm sure U+Investors doesn't care all of the people who had losses. Now U+Investors are in loss, don't think nakowa won't play anymore.
Let's be honest, If u find the winning strategy, or simply U have luck, won't U do the same?^^^
FACT: Investors on JD are always gambling although they might have an EV of -1%. However, because of variance, they might well lose from time to time, just as other gamblers do.