What a great opportunity for Trump to explain how business works. The reason that losses are deductible is because Congress wants to keep investors' money in play. Someone or group who risked capital, and hits a loss situation, will likely risk it again once they recover. On net, it's good for the economy. Of course, in a debate scenario, especially with the moderator interrupting the pro-business side 15 times, it's hard to explain the nuances of a capitalist economy. You have to sort of dumb it down for the average American, and then use bumper sticker phraseology so as to not lose people.