Because there was a total collapse of the commercial real estate market prior to this, in the late 80's.
His losses were prior to the "heat up", and Trump was legally able to claim his loss for several years to come, at least up to 1995. Just as Jeff Bezos (Amazon) did in 2000, GM did for several years after their bailout. And of course the Clintons legally did the same with their own personal taxes in 2015:
Three things wrong with your assertions.
Trump's losses are related to his casinos, his airline, and his purchase of the Plaza Hotel. They don't have much to do with commercial real estate. (I use the term "commercial real estate" to refer to office buildings, warehouses, and industrial parks that Trump might have owned and was renting out.)
Trump did not claim $916 billion of losses prior to 1995 and then claim this loss for several years to come. Trump claimed
a $916 billion loss IN 1995 and then was able to use that loss to offset any gains for years to come, probably at least 20 years to come, as the NYT speculates.
Clinton's claim of a $699,000 loss on capital gains is a one time write off. It does not carryover to future years. This is their personal taxes not a corporate tax return with retained earnings/losses. Corporate losses (or gains) are claimed annually and they increase or decrease with losses or gains in subsequent years. This is how the NOL (Net Operating Losses) work.