Why Protecting a Toxic Performer Is the Fastest Way to Erode Your Culture

Every leader has encountered that person.

They hit every target, dominate client meetings, bring in new business, and consistently “deliver results.”  On the surface, they’re a dream hire.  However, look more closely, and you’ll see the signs: junior staffers avoiding eye contact, nervous laughter in meetings, high turnover in their team, and a growing sense of emotional tension that no KPI dashboard can measure.

They are, as many leaders privately admit, both brilliant and brutal.  And too often, they are protected.

In many organisations, particularly in high-performance, margin-tight industries like advertising, tech, and consulting, this toxic high performer becomes a sacred cow.  Untouchable.  Whispered about.  Excused in the name of performance.  “Yes, but…” becomes the default defence.  “We can’t afford to lose them.”

What if that assumption is dead wrong?  What if keeping them is the most expensive decision you're making?

The Hidden Costs of a Brilliant Jerk

The numbers are not on your side.

A seminal study by Michael Housman and Dylan Minor (Harvard Business School) found that the net cost of retaining just one toxic employee outweighs the benefit of several top performers.  On average, a single toxic employee costs an organisation over $12,000 per year, not in salary, but in turnover, reduced morale, legal risk, and lost productivity.

And that’s just the tangible cost.

The real damage is cultural, and it spreads like mould.  Quietly. Systematically. Relentlessly.

When you tolerate a brilliant jerk:

• Psychological safety collapses: people stop speaking up, creativity dries up, risk-taking disappears.

• Collaboration breaks down: teammates avoid working with them or, worse, mimic their behaviour.

• Trust erodes: not just in that individual, but in leadership as a whole.

• Top talent walks: often silently and without exit interviews.

And here’s the kicker: once people see that bad behaviour is protected, they stop believing anything else you say.

Your values? Just words.  Your culture? Just theatre.  Your leadership? Just talk.

This Isn’t a Talent Problem. It’s a Leadership Problem.

At True North, we challenge leaders to face the a hard truth: 

What you permit, you promote.

By shielding one person because they’re a rainmaker, you’re sending a signal to the entire organisation: “Performance matters more than people.”

Whether you say it or not, everyone hears it.  This is most often heard in founder-led businesses or smaller teams where every client counts; the fear of losing a high performer feels existential.  If one person holds the entire business together, you don’t have a business.  You have a hostage situation.

Leadership means knowing the difference between productive tension and cultural corrosion.

The Turning Point: From Enabler to Leader

If you’re a leader reading this and thinking, I know exactly who that is, you’re not alone.  Recognising the problem isn’t enough.  The work begins when you shift from protecting performance to protecting your people.

The bravest leaders I work with aren’t the ones who make the hard call eventually.  They’re the ones who make it intentionally.

Before it becomes urgent. Before others leave. Before the culture calcifies.

And they do so by asking three essential questions:

• What am I afraid will happen if this person leaves?

• What message am I sending by keeping them?

• What unspoken permission am I giving others to behave the same way?

What Strong Leaders Do Instead

1. Set clear behaviour KPIs alongside performance goals.

   How someone achieves outcomes is just as important as what they achieve.

2. Run regular anonymous team pulse checks.

   Your culture isn’t what you think it is; it’s how people experience it.  Ask.

3. Coach early, not just at the exit.

   Toxicity is often a symptom: of burnout, insecurity, or unmet needs.  Don’t wait until it becomes irreparable.

4. Calculate the hidden cost.

   Put a dollar figure on attrition, rework, morale dips, and missed opportunities. Leadership decisions land harder when tied to real numbers.

Final Thought: Who Are You Willing to Lose?

If the answer is "anyone but them," you’ve already lost more than you know.

Great culture isn’t built by clinging to the toxic top performer, it’s built by protecting the people doing the quiet, good, values-aligned work every single day.
 Are you rewarding results? Or role modelling?
 Are you managing for metrics? Or for meaning?

So, ask yourself:

Are you rewarding results? Or role modelling?

Are you managing for metrics? Or for meaning?

At True North, we work with leaders ready to stop outsourcing their standards for short-term comfort.  We help you build cultures where performance and integrity are non-negotiable, and where leadership means protecting what matters most.

Real leadership isn’t about who you keep.  It’s about what you stand for when it counts.