There are billions of potential customers on this planet. And theoretically, you could sell anything to some of them as long as you've won over their trust. So I think the assumption that a niche is a must is overstated.
That said, the real issue that new dropshippers are running into is that it's a lot harder to find reliable suppliers where you can sell their goods at a decent profit margin, since the average customer is now very sensitive to cost/delivery thanks to Amazon/Walmart. Aliexpress suppliers have gotten wise to the dropshipping game in the US and are now either pricing their products accordingly or competing directly with the dropshippers on American marketplaces, which has really cut into dropshipper's margins. On top of that, 3rd party marketplaces have effectively banned dropshippers from using their platform, which makes it virtually impossible to get into the dropshipping without any overhead costs or little manual effort.
However, if you can somehow find a supplier that's willing to dropship items for you at/just above cost, you have the budget to build a professional-looking store and the money to advertise your product/store, dropshipping is still a lucrative way to earn money.
