Twenty-five years ago Jeff Emalaba was a guest host on CNBC Africa, analyzing derivatives, commodities and futures, and holding an options license in Florida. He describes all of it as one subject: risk transference. That is the lens he brought to real estate, which makes what happened next harder to explain and more useful to hear. He drove two hours to see a duplex in North Carolina and walked it with his agent. Nothing looked wrong. He asked the seller why the previous buyer had backed out...