President Trump isn't exactly a man of mystery. He has willed himself to be a public figure for more than 30 years, has written numerous books about himself and seen others written about him, hosted two conjoined reality TV shows, and was a staple of cable TV, talk radio, and tabloids for many, many years. He appears to lack basic impulse control — his Twitter account seems bio-electronically connected to his id — but we don't know that for sure. In fact, while it is hard to think of something that hasn't already been written about Trump, there are lots of things we don't really know.

Does he like being president? Maybe. Is he happy in his marriage? That's not really our business. Did he really not think America was great before his election? As Sean Spicer might say, his slogan speaks for itself. Does he believe all the untrue things he says? Who knows? Willful belief is a powerful drug. Is he mentally stable? That's inappropriate to judge without a proper in-person analysis by a trained professional. Does he really want to help blue-collar workers in small-town America? Probably — don't you? Why are Trump's policies so in line with Russian President Vladimir Putin's, a U.S. adversary that almost certainly meddled in the U.S. election? There are multiple investigations looking into that.

Speculation about Trump and his madcap White House life is now its own industry, and to some extent Trump must appreciate the attention. But we know one important thing about Trump with rock-solid certainty, and it's easy to lose sight of amid all the smoke and mirrors, bread and circuses, Sturm und Drang.

It is this: Donald Trump does not care enough about the American presidency to give up his business for it. It was a job he didn't think was worth releasing his tax returns to obtain, and now that he has it, Trump has shown zero inclination to let the public know what conflicts of interest his tax documents might reveal, or to take the steps necessary to appropriately minimize the conflicts we know about.

This is not President Jared Kushner, a young man just beginning his career in the high-stakes world of real estate development. Trump is 70 years old, five years past retirement age. He is worth anywhere from a few hundred million dollars to several billions, certainly enough money to live lavishly on interest alone for the rest of his life.

The idea of public service is that you serve the public, not vice versa, and Trump is now America's foremost public servant. Presidents are not forced to wall off their previous businesses and assets to avoid the conflicts of interest that arise when you are the most powerful person on earth, and your decisions move and shape markets. But they always have done so, because the presidency is an honor and more importantly a grave responsibility, and they respect that burden and that gift. Presidents need to be all-in, and Americans need to know that the president is making decisions to serve the country's interests, at least as he sees them, and not his own.

Most presidents put their assets in blind trusts, where they no longer control or know where their assets are invested. Richard Nixon liquidated all his assets and bought two houses. Jimmy Carter voluntarily gave up his beloved Georgia peanut farm business, and he was only 52. He explained why after his victory in 1976:

Well, it was a hard decision for me to make and this is something that I've had to face. I've literally given up my own method of making a living here in Plains. And almost everything you see down here behind us, a lot of this stuff I built with my own hands, even before Billy came home from the Marine Corps. But I don't have any regrets about it. But I don't want any decision that I make as president to have any effect on my own income. The trustee will try to do the best they can and take care of my remaining family here, my mother and Billy, not to disrupt their lives too much. [Jimmy Carter]

His brother Billy, it turns out, siphoned enough money from the farm that Republicans in Congress named a special prosecutor to investigate where Carter's money was going (President Carter was exonerated; Billy Carter had a beer named after him).

Nobody expects Trump to be Jimmy Carter. But Trump has essentially only given over day-to-day control of his business to his two oldest sons, and he is the sole recipient of his not-blind trust. Unlike Carter's peanuts, Trump's licensing and resort business stretches into countries all over the world, including places like Turkey and Kazakhstan. The Atlantic has a running list of Trump's potential conflicts of interest and arguable violations of the Constitution's Emoluments Clause, and it is growing long.

"I don't think divestiture is too high a price to pay to be the president of the United States of America," Walter Shaub, the long-suffering head of the U.S. Office of Government Ethics, said in a softly blistering speech at the Brookings Institution in January. Donald Trump clearly thinks it is too high a price, and whatever his other strengths or weaknesses as president, you should never forget that.