Countless business rivals have learned the lesson the hard way – but the media has been slow to catch on.
Don't mess with Donald Trump.
Several media outlets have practically made a sport out of attacking President Trump with hit pieces and scandalous allegations.
And his millions of supporters have struck back.
Now, two of the worst anti-Trump media offenders – sports network ESPN and Internet news site BuzzFeed – are in hot water.
Both media companies announced massive layoffs just this week.
ESPN will be cutting 150 staff as part of a move to save $100 million – just months after it laid off another 100 people.
ESPN has drawn the ire of Trump and conservatives for months, as on-air personalities consistently defended National Football League players who chose to kneel during the national anthem.
And the network was notoriously lenient after host Jemele Hill publicly called Trump a white supremacist on Twitter.
ESPN has lost nearly 1 million subscribers since the start of the year, with many of those losses coming from pro-Trump households.
"The NFL and ESPN badly misjudged Trump. Now they're paying the price," CNN reported in October (and, for the record, CNN is paying the price, too).
Trump's second media victim this week is BuzzFeed – and conservatives couldn't be happier about it.
It was BuzzFeed that published the so-called "Trump Dossier" in January, full of scandalous allegations against Trump that have since been debunked.
Now, BuzzFeed has announced that it is laying off as many as 100 people.
BuzzFeed's traffic has consistently decreased since earlier this year, and the site had 8 million fewer readers in October than it had the previous year.
And you can bet that BuzzFeed isn't drawing much traffic from Trump fans.
The media has spent months trying to bully Trump. But they're learning the hard way that he has a loyal army of millions of supporters.
And trying to smear our president is very bad for business.