Killing Bill: The Demise of Bill O'Reilly at Fox NewsWhen one of the most powerful men in media gets fired, it proves that everyone is expendable.

Last week's abrupt ouster of Bill O'Reilly atFox News震惊了世界媒体。他的黄金时段节目,O'Reilly Factor, was the top-rated cable news program for 15 consecutive years, bringing in about $150 million in annual ad revenue. But he was forced out over sexual harassment claims and a growing ad boycott.

The fact that such a powerful political pundit with that kind of track record proved to be expendable is all the proof you need to know thatwe are allexpendable. Every employee, no matter how important to the company, is expendable. That includes top executives and founders, as formerFox NewsCEO Roger Ailes learned last year.

Whether the allegations against O'Reilly and Ailes are true is immaterial. Regardless, two of the most influential men in the media universe went down for the same reason, under the same conditions, at the same company -– a company where they had every reason to believe their jobs were safe.

If it can happen to them, it can certainly happen to you. There are lessons to be learned, so pay attention.

Bosses need to keep their noses squeaky clean.

Maybe you would never harass or bully an employee, but merely the accusation of impropriety can turn sentiment against you. Perception is reality, and when it comes to sexual harassment, accusers seem to get the benefit of the doubt. Since you're probably an at-will employee or contractor, you can be fired at any time, for any reason.

Remember, neither of these men admitted to any wrongdoing and both were under contract. It made no difference. The point is, dipping your pen in the company ink, as the saying goes, is not such a good idea. Neither is spending time alone -- especially off-site in a social setting -- with a worker that you happen to be attracted to.

Related:Uber CEO Travis Kalanick Launches Investigation Into Sexual Harassment Claims

Heed the power of the hashtag.

When news broke thatFox News and O'Reillyhad paid out $13 million to settle five sexual harassment claims against him, that started a social media backlash calling for advertisers to boycott The Factor and for its host to be fired. About 50 advertisers caved. Fearing that viewers would follow, Fox News soon caved as well.

Here's the thing. Protest is protected speech under the First Amendment, as it should be. But we live in an era where activists with big money backers and lawyers can fire up a social media firestorm faster than you can say #BoycottUnited or #DeleteUber. Whether the protest is legitimate or not makes no difference. Like it or not, executives will often give in to pressure to protect their brand ... and their bottom line.

Related:What's Next for United After Dragging a Bloodied Passenger Off a Plane? A Plan.

He who lives by the sword, dies by the sword.

One of theNew York Timesreporters who broke the story,Emily Steel, was once threatened by O'Reilly on air for her reporting on the early days of his career. "I am coming after you with everything I have," O'Reilly said. "You can take it as a threat." Steel says that had nothing to do with her recent coverage, but that's neither here nor there. That sort of vehemence was not unusual on The Factor.

O'Reilly was known for a willingness to go toe-to-toe with those he felt unfairly maligned him. He could be combative and aggressive over issues he felt strongly about. That's not unusual among powerful leadership types, nor is it necessarily a bad thing. But that kind of behavior does create enemies and raise the risk that one of them may come back to haunt you someday.

Related:Here's How to Gain Respect Instead of Making an Enemy

Everyone is expendable. Everyone.

As a 20-plus-year alum and former senior executive of the tech industry, I can tell you from personal experience that practically nobody has a permanent job. I've seen once-respected CEOs, founders and star performers fall from grace in a heartbeat. I've been fired myself, more than once. It's never pleasant and it isn't always fair, but that's how it works. In my opinion, that's exactly as it should be.

Don't get me wrong. I do believe the pendulum has swung too far in the direction of political correctness in the workplace. I don't think leaders should kowtow to bullying activists or thin-skinned whiners who get offended at the drop of a hat. But I draw a hard line at using hire-fire power to gain favors, sexual or otherwise. And I'm a staunch supporter of meritocracy.

Many people long for the good old days when you spent your life working for one company. I'm not one of them. The current situation of at-will employment where we all manage our own careers is far more closely aligned with free-market capitalism. The workplace should be governed by free market competition, as well.