Quite often those who have come out as losers whether in a deal, employment, etc. against Trump or anyone else quite often are discouraged from or simply don't have the time or money to take him or anyone else to court. For example, there are some individuals who were looking to better their lives financially by learning the ropes of real estate investing/development/etc. who say they got screwed by Trump typically for sums of four or five figures at a minimum and at least some of them are part of at least one of two separate class action lawsuits against the defunct Trump University.
Also, it could be argued that the hundreds of employees at two different Atlantic city Trump casinos that went bankrupt got screwed because they clearly sought stable work that was not so. Trump has bankrupted several companies which is an unfortunate aspect of business but, I do find it odd and a bit irritating that nearly everyone I've happened to see speaking of his business success completely leaves out his various failures and speak as if he makes no mistakes or missteps because he has made many and he is human just as we all are.