Trump had been involved in 4,000+ lawsuits before he ever rode down that escalator in 2015. He's not in legal trouble because he's running for president. He's running for president to escape his legal trouble.
He was shocked when he won in 2016. "The election was rigged" went out the window and "how can I exploit the presidency" (sell access & info) became the new business plan. Now he sees the presidency as a giant get out of jail free card. And then jail everyone who opposed him.