Even in a non-zero sum model, each investment needs to justify itself vs. alternatives at the time. I may have a wealth of investments that can have guaranteed

Even in a non-zero sum model, each investment needs to justify itself vs. alternatives at the time. I may have a wealth of investments that can have guaranteed positive returns, but I must choose which to invest in at any time with limited resources. Even if I can expand available resources because of the promise of these alternatives, or through reinvestment of gains, I still must choose what to do at any time, until I have enough resources to pursue all promising avenues simultaneously.