Combining investments that don't all move together lowers your overall ups and downs, without necessarily lowering your expected return. That's a real benefit you get without giving something up in exchange — rare in investing, where most trade-offs cost you something.
Beyond holding multiple companies, real diversification spreads across asset types, industries, and regions. A portfolio can look diversified on the surface but still carry hidden risk — ten companies that are all in the same industry and region can move together in a downturn, no matter how many you hold.
It's natural to feel more comfortable investing in companies and markets you recognize. A small home market can end up making up too much of a portfolio, compared to its real size in the global economy. It's worth checking this on purpose, instead of ending up there by default.
The UAE and the wider Gulf region are a small slice of global markets by size. That's not a reason to avoid local investments — it's a reason to check, on purpose, whether a portfolio is more concentrated there than intended, instead of ending up that way just because it's familiar.