An index fund doesn't try to pick winners. It simply buys every company in a given index, in roughly the same proportions as that index — and that's the entire strategy. No fund manager is guessing which stock will do best next quarter; the fund just mirrors the market it tracks.
Say you put AED 1,000 into a fund tracking the Nasdaq-100, an index of 100 large US technology and growth companies. That single AED 1,000 instantly buys you a tiny stake in all 100 — a few dirhams' worth of a chipmaker, a few more in a cloud software company, a slice of a consumer electronics giant, and so on. If one of those 100 companies has a terrible year, it barely dents your total, because it was never more than a small fraction of your AED 1,000 to begin with. Compare that to putting the full AED 1,000 into just one of those companies — a bad year for that single company means a bad year for your entire investment.
The same idea applies locally — the DFM General Index tracks a basket of companies listed on the Dubai Financial Market, rather than one single stock. Buying exposure to an index like that means your result depends on how the whole market performs, not on correctly guessing which one local company will outperform the rest.
A single fund that buys a small slice of hundreds of companies at once, so you own a piece of the whole market instead of betting on one stock.