One loss means that you also forego all future gains. Losses are irreversible and extend in the future. Sadly, relationships, careers, investments, and sports often share this undesirable property. <ul><li>in most real-life situations, we have a limited number of trials.</li><li>How much are you expected to win if you play Russian Roulette a hundred times? </li><li></li></ul>

In any repeated activity, irreversibility absorbs future gains

The barbell strategy consists of exposing most of yourself to safe activities and a tiny bit of yourself to risky ones with high upside.

When we consider averages, the good offsets the bad. However, for individuals, something good happening to someone else doesn’t offset the bad that happened to them

In single instant of time, pure performance is all that matters. Instead, over a prolonged period of time, survival dwarfs performance.

Sports. The harder you practice, the faster you progress. However, if you try too hard, you might injure yourself. Irrecoverable damage at your joints might end your ability to perform the sport well, or at all.-Career. The harder you work, the more chances you have for professional success. However, if you work too many hours for too long, you might endanger your health, marriage, or mental sanity. Once lost, these are hard, if not impossible, to recover. A single negative event can render short-term maximization irrelevant.

If the population and lifetime outcomes differ, the system that produces them is non-ergodic. You can only rely on expected outcomes if you are guaranteed a large number of repetitions.

The population outcome is the outcome of many people performing an action once. The lifetime outcome is the outcome of one person performing an action many times

Russian Roulette is non-ergodic because the lifetime outcome differs from the population outcome. If you decide to keep playing it because you fail to grasp its non-ergodicity and mistakenly believe that your lifetime outcome equals your population one, you will end up dead.

In ergodic systems, you can use the population outcome to make optimal decisions. In non-ergodic systems, you cannot.

When losses are irreversible, or when losses preclude future gains, do not decide based on averages. Instead, use more granular data. Ask yourself what might happen to you. Ask yourself if and how unexpected losses can negate your future plans

Some reviews of Luca's previous books "This book is like a magnificent suspension bridge, linking the science of the human brain to the practical craft of applying it in everyday life. I loved it." – Rory Sutherland, Ogilvy's Vice Chairman “So insightful with common sense applications of Complexity and the ability to communicate clearly!!” – Bob Klapetzky. “A SUPERB book [...] by one of the profound thinkers in our field [behavioral economics].” – Michal G. Bartlett What's ergodicity, and why it matters? "The Most Important Property to Understand in Probability, in Life, in Anything." – Nassim Nicholas Taleb on ergodicity. "I think the most under-rated idea is ergodicity." – David Perell, author. Is ergodicity the most important concept in decision-making and behavioral sciences? (Yes.) Is it relevant for you in your daily life? (Yes.) Is it possible to explain it so simply that a grandma or a high-schooler can understand it? (Yes.) Even if they know nothing about maths? (Yes.) That's because ergodicity is an important idea with so many practical applications. Sadly, most books describe it in a very technical way, making it inaccessible to most people. In this short book, 6-times author Luca Dellanna describes ergodicity as simply as possible. You will read stories about how not knowing about it destroyed his cousin’s career as a skier, or how misunderstanding it caused additional deaths during the pandemic. You will learn how to spot situations in which ergodicity matters and the three strategies to react appropriately. The book is approximately 169 pages long, of which 143 are pure content and the rest tables of content, etc. Who is this book for? This book is for readers interested in growing themselves, their career, or their business, and who want to learn about ergodicity and its practical applications without having to understand its mathematical foundation. No mathematical knowledge is required, only a high-school level understanding of English. Readers who want to master the theory and mathematical foundation of ergodicity are better off reading a more formal manuscript. This book is not a substitute for it, but a complement. About the author Luca Dellanna is the author of 6 books. He is a researcher in complexity science and emergent behaviors, and an operational excellence consultant. He spoke at Nudgestock and regularly teaches risk management in masters. His personal website is Luca-Dellanna.com and his Twitter is @DellAnnaLuca.