About six months ago, a friend and I were talking about the 2020 presidential elections when he shared a startling prediction: President Trump would not seek re-election.

Despite the fact that my friend is politically connected, brilliant and often right when others are wrong, I thought, "no way, no how." Trump's overweening ego is too bloated for him to simply walk away from the most powerful post on the planet. And by all accounts, he's masterfully redefined the office to suit all his self-centered needs.

He works only when he wants to, reportedly dedicating as few as three hours a day to governing and devoting the rest to "executive time," or watching television and tweeting.

He skips the traditional obligations most presidents have fulfilled, from holding regular press conferences to honoring our veterans at Arlington National Cemetery on Veterans Day. If it's not important to him, conventions be damned.

And he's managed to bend the will of Republicans in Congress to his version of politics, which often looks nothing like theirs, getting easy cover for bad policies like tariffs or a trillion-dollar spending bill, as well as for his near-constant perversion of conservative values.

He's earned not only forgiveness but praise from many Republican lawmakers for subverting the rule of law, distorting the norms of basic human decency and regularly scoffing at the primacy of our founding document, the Constitution.

Why on earth would he leave all this behind?

I'm now beginning to understand what my friend was imagining when he said Trump wouldn't run again. And I think he may be right. Here's why.

He's running out of stooges

Life was easy when Trump's inner circle was happy to protect him from outside pressures. Republicans shielded him from investigations, and his aides carried out his imprudent ideas. But that's all falling apart.

In a Hail Mary attempt to keep the Robert Mueller investigation at bay, he's appointed Matthew Whitaker to head up the Justice Department. But that is, even by Trump's own admission, temporary. No one person can keep the investigation from running its course. Democrats will see to that, and then some. The investigations, subpoenas and hearings coming Trump's way will be the equivalent of a root canal, and there's little he can do about it.

He trusts no one

He's reportedly preparing to fire Homeland Security Secretary Kirstjen Nielsen and Chief of Staff John Kelly, and first lady Melania Trump issued her own unusual call for deputy national security adviser Mira Ricardel to be fired. As Washington Post White House bureau chief Philip Rucker suggested on Wednesday, "There are not particularly the sort of close loyal friends that he feels he can confide in with any regularity at a deep emotional level."

The castle is crumbling from the inside, and Trump is feeling like a ruler under siege.

His base is shrinking

The midterm elections proved one thing: Trump's base is not as big as it once was. He's lost a considerable contingent in the suburbs, and he will not likely have the turnout he did in 2016 by 2020. Nor will he have as singularly horrible an opponent.

The circuitous and uniquely favorable path that led to his first win will have vanished, leaving not even breadcrumbs behind.

It's not ego that drives him

It's easy to assume, as I said above, that ego is Trump's main motivator. But it's actually his irrational, impulsive, insatiable id — the dominant part of his brain that craves immediate gratification and self-soothing affirmation at all times. He wants what he wants when he wants it. As he gets less of what he wants, and has fewer people willing to bend the rules to help him get it, it's quite easy to imagine Trump impulsively deciding someday in the next year or so that he's had enough.

The 2020 elections are light years away by political standards. We know Trump's biggest brand is never running away from a fight, and in the end that might trump everything. Anything can happen — but little of that is likely to favor the president.

The next few months will be bloody and exhausting for all of us, but for the president they might just be too much to take.