The Let Them Theory
April 22, 2025
4 min read
📚 arvy's Book Club
arvy's Teaser: 100,000 copies a week. The #1 non-fiction bestseller of 2025. Mel Robbins' "Let Them Theory" struck a nerve — because it addresses something everyone struggles with: the urge to control what others think, do, and decide. But here's the surprise: the book's core idea is also one of the most powerful principles in investing. Let the market crash. Let others panic. Let the noise be noisy. Focus on what you control. Here's why.
The Book in 60 Seconds
The Let Them Theory (2025) by Mel Robbins presents a simple but radical idea: when someone wants to do something — let them. Stop trying to control other people's behaviour, opinions, and choices. Instead, redirect all that energy inward: protect your peace, clarify your values, and focus on your own actions. It's not passivity — it's strategic disengagement from things you can't change anyway.
Mel Robbins · 2025 · Self-Development & Mindset
Idea 1: Control Is an Illusion — And It's Exhausting
Robbins' thesis starts with a psychological truth: most of our stress comes from trying to control things outside our control. Other people's opinions of us. How colleagues behave. Whether someone texts back. Whether our family agrees with our choices.
Every hour spent worrying about what you can't change is an hour not spent on what you can. Robbins argues that letting go isn't giving up — it's strategic resource allocation. Your mental energy is finite. Spend it on your own actions and decisions, not on policing other people's.
You can't control the weather. But you can choose whether to carry an umbrella.
The Investor Lesson
Replace "other people" with "the market" and Robbins' theory becomes an investing masterclass. You can't control interest rates, geopolitics, AI disruption, or whether the market drops 20% tomorrow. You can control: how much you invest, how diversified you are, whether you panic-sell, and whether you keep your savings plan running. Let the market do what it does. Focus on your system.
Idea 2: Let Them Show You Who They Are — Then Decide
Robbins' second insight: when you stop trying to change people, they show you who they really are. And that information is invaluable. Instead of projecting what you want them to be, you see what they actually are — and can make better decisions about who to trust, invest in, and build with.
This applies to relationships, friendships, and work. But it also applies directly to investing.
The Investor Lesson
Let companies show you who they are. Don't project your hopes onto a stock. Look at the evidence: are earnings growing? Is management honest during downturns? Is the moat widening or shrinking? Quality companies reveal themselves through consistent behaviour — just like people. Trust the data, not the narrative. (→ Quality Investing)
Idea 3: Letting Go Creates Space for What Matters
Robbins' deepest point: when you stop reacting to everything, you create space — for clarity, for peace, and for intentional action. The constant emotional churn of trying to control outcomes — checking your phone, arguing online, worrying about what people think — is what Robbins calls "emotional labour without return."
Letting go doesn't mean not caring. It means caring about the right things, with the energy you've freed up from the wrong ones.
The Investor Lesson
The best investors do less, not more. They check their portfolio quarterly, not daily. They ignore market commentary. They don't react to headlines. The energy they save goes into the things that actually matter: earning more, saving more, and living well. Automate your investing and free up your mind for your life. (→ Ikigai — Book Club)
What This Means for Swiss Investors
| "Let Them" Principle | Investor Application |
|---|---|
| Let them panic | When the market crashes, let others panic-sell. Your savings plan buys more shares at lower prices. Crashes are discounts for those who keep investing. (→ Savings Plan) |
| Let them predict | Let pundits, analysts, and Twitter predict the market. Nobody can. Focus on what you control: your savings rate, your investment horizon, your diversification. |
| Let them judge | Let others judge your financial choices. The 3.5-room flat instead of the 4.5. The used car instead of the lease. Every CHF not spent on appearances compounds silently. (→ Psychology of Money) |
arvy's Take
What holds up: Robbins nails something universal: the exhausting desire to control what can't be controlled. The "let them" reframe is genuinely freeing — and its application to investing is uncanny, even if unintentional. The book isn't deep philosophy, but it doesn't need to be. The simplicity is the point.
What's missing: This is a self-help book, not an investing book. Robbins doesn't make the financial connection herself — we're making it for her. The writing is repetitive at times (the core idea could be a long article, not a 300-page book). And the relentless positivity occasionally feels shallow.
What we'd add: The "Let Them" theory is the Stoic investor's philosophy in modern packaging. Marcus Aurelius said it 2,000 years ago: focus on what's in your control. For Swiss investors, that means: max your 3a, automate your savings plan, check quarterly, and let the market do whatever the market does. The compound interest doesn't need your attention. It needs your patience.
3 Sentences to Remember
1. Control is an illusion — in life and in investing. Focus on what you can change: your savings rate, your investment horizon, your behaviour.
2. Let the market crash. Let others panic. Your savings plan buys more shares at lower prices.
3. The best investors do less, not more. Automate your system and free your energy for your life.
Buy the book
English (Amazon) · Deutsch (Amazon)
Also in Book Club: Psychology of Money → · Ikigai →
Let them panic. You stay invested.
Automate your savings plan. Max out Pillar 3a. Let compound interest do its work in silence. From CHF 1/month.
This article was written by Patrick Rissi, CFA, Co-Founder of arvy, and reviewed by Thierry Borgeat and Florian Jauch, CFA.
Disclaimer: This article is for general informational purposes only and does not constitute personal investment advice. Amazon links are affiliate links. arvy is a FINMA-supervised asset manager.
