Depends...
Were his bankruptcies total liquidation (chapter 7) or debt restructuring (Chapter 11)?
If Donald Trump's bankruptcies were under Chapter 7, then they should trouble anyone who supports him on the basis of his business acumen, as a "job creator". For if nearly every business venture you've tried has failed due to insolvency, then you're not a very good job creator are you?
If, on the other hand, his bankruptcies were under Chapter 11, then I think most people could give him a pass presuming that his business(es) as reorganized are thriving.
As an aside, I think what should troubles the voters more isn't his bankruptcies of the past, but rather knowing whether or not any of his existing business ventures have grown and, if so, how many people he's employed over the years in those businesses. Growth being the key word here. If his employment number have remained constant, then it would indicate that his business(es) aren't growing and that would nullify his claim of being a "job creator" of the caliber that his supporters are seeking from him.