Diworsification - the investing mistake nobody talks about enough
Peter Lynch coined the term "diworsification": adding so many positions to a portfolio that you end up recreating the index, but less efficiently. More fees, more complexity, same or worse returns.
The benefits of diversification plateau after a certain point. Beyond that threshold, extra positions don't meaningfully reduce risk, they just dilute conviction. And if your holdings overlap more than you realise (multiple ETFs all heavy in the same mega-cap stocks, for example), you're less spread out than you think.
Under-diversification has its own problems, obviously. But the "more is always better" assumption is worth questioning.
Where do you draw the line?