💀The Deadly Sins of PM
A cheat sheet of the failure modes that derail PM careers — most of which are completely avoidable.
Most PMs who flame out don't flame out from a single huge mistake. They flame out from accumulating 4-5 small patterns of bad behavior that compound. Knowing the patterns means you can audit yourself and avoid them.
The seven most common deadly sins: (1) acting like a CEO, (2) being a feature factory, (3) hiding from data, (4) over-promising, (5) bad writing, (6) not knowing customers, (7) taking credit. Each one is a slow career poison; together they end PM careers.
The seven sins
1. Acting like the CEO of the product
You don't have CEO authority. The 'CEO of the product' framing dates you and makes you bossy. PMs lead through influence; the sin is asserting authority you haven't earned.
2. Being a feature factory
Taking stakeholder requests and turning them into features without questioning whether the underlying problem is real. Outcome: lots of shipped features, none of which move metrics. Career outcome: you get a reputation as a coordinator, not a leader.
3. Hiding from data
The PM who can't run a SQL query, doesn't read experiment writeups, and makes product decisions on opinion alone. In 2026 this is a fireable offense in most growth or AI PM roles.
4. Over-promising
Committing to dates without checking with engineering. Committing to features without checking the discovery. Once the trust breaks, it's nearly impossible to rebuild.
5. Bad writing
PRDs that engineers can't parse. Strategy docs nobody reads. Slack messages that take three reads to understand. Writing is the PM's #1 medium of leverage; weak writing caps your career.
6. Not knowing customers
The PM who hasn't talked to a customer in three months but writes confident PRDs based on assumptions. The product reflects this — features that solve problems nobody has.
7. Taking credit
Claiming engineering's work as your own. Speaking in 'I' when the team did it. Engineers see it; they stop trusting you; your career stalls.
The cumulative pattern
Most failed PMs commit 3-4 of these simultaneously. They don't know they're doing it. The fix is auditing — once a quarter, honestly ask yourself: am I doing any of these?
Better: ask a peer or your manager. They probably know.
The corollary virtues
- Lead through influence, not authority
- Push back on stakeholder asks; ship outcomes
- Be the most analytical person on your team
- Under-promise, over-deliver
- Write as if your career depends on it
- Talk to 3+ customers a week, forever
- Spotlight engineers and designers; share credit relentlessly
Real-world examples
A common pattern in failed PM resumes: 'I built X, I launched Y, I drove Z.' Engineers reading these resumes immediately discount them. Compare with strong PM resumes that say 'partnered with engineering and design to ship X, which moved [metric] by [amount].' The shift in language — and the underlying sin — is visible.
Go deeper — recommended reading
Interview questions (1)
Q1What's the worst pattern you've seen in PMs?behavioralmid▼
The pattern I've seen most often: PMs who act like the CEO of the product. They assert authority they haven't earned, override engineers and designers on craft decisions, and take credit when things work. Engineers stop bringing them hard problems; designers go quiet in reviews; the team's velocity drops.
The fix is the opposite move: lead through influence. Bring problems to the team, not solutions. Trust craft to the experts. Share credit aggressively. Build the kind of relationships where engineers will spontaneously work harder for you, not because you told them to but because they trust you.
I've worked on both kinds of teams. The 'CEO of the product' teams ship less, even though it looks busier. The influence-led teams ship 2-3x more.