An index fund copies a list of companies instead of picking a few. Buy one share of a world index fund and you own a tiny slice of over 1,200 companies at once.
Nobody has to guess which company comes out ahead. The fund holds the best and the worst together, in proportion to their size, and simply moves with the whole group.
Put €10,000 into one world index fund and it is spread across dozens of countries and sectors automatically, not because you chose each one, but because the index did.
An index fund still falls when the whole market falls. Spreading across companies removes one risk, not every risk.
A fund's key information document names the index it tracks. Portfolio shows what you actually hold underneath any fund.
An index fund owns the whole group, the best and the worst together, in one simple buy.
Count the companies in one world index fund.