Never in 250 years has America witnessed a sitting president shield himself and his family from tax scrutiny, after leveraging policies that benefit his own businesses and personal portfolios, as Donald J. Trump has done. Why it matters: This isn't a hidden scandal. Trump has done this publicly and proudly . Last year, we called it the "most unprecedented presidency in 250 years." In doing so, he has set a precedent — once so unfathomable as to be laughable — that it's OK for presidents and family members to make billions off deals affected by government decisions, then use the Justice Department to secure lifetime protection from scrutiny of their past tax returns. Trump's crypto venture alone has been a windfall unlike anything in the history of presidential business, generating more cash for the Trump family in 16 months than the entire Trump real estate empire produced from 2010 through 2017, according to The Wall Street Journal . "I let my kids ...…