In 2014 and 2015 Trump paid $50,000 for fake polls. In 2014 he was trying to establish himself as a top 100 business leader. In 2015 he was trying to establish himself as a campaign frontrunner. When he was on top, he started most interviews with “did you see my polls?”
Verified 1/17/2019: WSJ first reported this news. This info is reportedly backed up by 2 Trump org emails. And, confirmed by Michael Cohen! Cohen is only contesting that it was done with cash. Cohen says it was a check.