I thought filing for bankruptcy was smart? Isn’t that what he said before about his previous bankruptcies?

Different kinds of bankruptcy, but essentially he said they were smart, business decisions: https://www.politifact.com/factchecks/2015/sep/21/carly-fiorina/trumps-four-bankruptcies/

“Hundreds of companies” have filed for bankruptcy, Trump said earlier in the debate. “I used the law four times and made a tremendous thing. I’m in business. I did a very good job.”