There's almost nothing harder than walking away when the time comes. Much of entrepreneurship focuses on the rise up, the hard work, grit and scrappiness it takes to get a business up and running and make it successful. Sure, we give mention to failure – builds character, and all that -- but we (rightfully) celebrate success even more.

But sic transit gloria mundi. Our fame, our professional glory lasts but an eye-blink of universal time. In the end, those accomplishments you hold so dear molder in the ground along with you. They aren’t worth clinging to.

It’s an important reminder looking at the drama at Viacom. Sumner Redstone, at an over-ripe age of 93, has decided to fight to retain control of his company, amid questions about his own competency, the loyalty of directors and the direction of Viacom. It is an especially brutal war, with Redstone following the advice of Dylan Thomas that, “Old age should burn and rave at close of day.” No one can say Sumner Redstone isn’t raging against the dying of the light.

It may be personal heroism, but it is professional suicide. Redstone literally has nothing to lose from a graceful exit. There isn’t a single person who can question what Redstone built at Viacom. Yes, Redstone perhaps made some personal errors, particularly with his wives and girlfriends (our author coughs uncomfortably), and not every deal he did was a good one. But Viacom is a media giant solely through Sumner Redstone’s force of will, and that is something for which he should sit back and look upon with pride.

But he is fighting, and that raises questions about his competency, his sanity, and -- worst of all -- his business acumen. No one wins in a fight this vicious, certainly not the shareholders who have entrusted so much of their personal treasure to Redstone’s leadership. And that’s a shame because, despite how the entrepreneurship world might lionize founders, companies have two higher priorities: their customers and their investors. The best CEOs and founders know this. They spend the vast majority of their time making sure customer experiences are strong and their boards (the highest touchpoint of the investors) are informed about strategy and execution.

Related: How an Entrepreneur Should Never Behave

Where it goes wrong is when founders don’t know when to leave. The best simply fire themselves, stepping aside for the best interests of the company. The worst hold on too long. Gurbaksh Chahal is probably the most extreme example. He stayed head of his startup, RadiumOne, even as he faced 45 felony counts related to charges he assaulted his girlfriend 117 times in a 30-minute period. If anything, he seemed to be more brash during that time, seemingly offended when people didn’t want to do business with someone under the cloud of domestic violence.

When he ultimately pled guilty to misdemeanor charges, his board fired him, even though Chahal was a significant shareholder. Rather than fade away, he fought back, painting himself -- not the victim of his abuse -- as a victim and blaming everyone around him but himself. RadiumOne wasn’t served by such behavior.

Related: How to Know When to Change Direction

There are cases where a fight back is appropriate. I still believe Men’s Wearhouse made a critical error in firing founder and CEO George Zimmer, who remains one of the keenest marketing minds in American business. But, for the most part, when things turn sour, it’s usually a good idea to step back and leave with your dignity, your reputation and your shareholders’ value intact.

Yet, it’s usually not in our nature to do that. Most divorced people I know talk about the first time they knew their marriage was over, and it usually predated the actual separation by years, with periods of counselling or “staying together for the sake of the kids” in between. Many people fight to keep jobs with no growth prospects simply because they don’t want to bother making a move. Inertia is one of those laws of physics and business that’s difficult to fight.

Related: Are You Quitting Too Soon or Staying With It Too Long?

It’s an even tougher battle because of the nature of entrepreneurship. Entrepreneurs, after all, are a different breed of cat. They’re more driven than the average person. Even though they could benefit from a little doubt from time to time, entrepreneurs are more likely to have absolute and unshakable faith in their ideas and their competency in carrying them out. It’s what makes them great founders, but it’s also what makes many of them subpar CEOs. As companies scale, most leaders know that the team that got a company to a certain point is very often not the team that will take you to the next level. That’s especially true of founding executives. Trouble is, they don’t see that.

Which brings us back to Redstone. Pyrrhus of Epirus handedly beat the Romans in two huge battles but he never conquered Rome. All he got was his name slapped for eternity on the term Pyrrhic victory (which is one you never want to have). Pyrrhus, though, wasn’t fighting for his ego alone, like Sumner Redstone is. Conceding this fight will only enhance Redstone’s justifiably admirable reputation and send an important leadership lesson to other founders and CEOs that the cost of some wars in too high to fight.