Well wholesale gives you better prices because you are buying in volume. The more you buy, the better per unit price you get (up until a point of course) So when you are buying in bulk like that, the wholesaler can then get a better price form the manufacturer because they are selling more product and then the cheaper prices start to flow through the entire chain.
With dropshipping, you are buying just one product, so the opportunity to get volume discounts isn't there.
Both methods have their advantages and disadvantages, it's more a choice what best suits you.