DJing requires actually possessing the music, and is usually collected in bulk, as even those DJs who are also producers rely heavily on tracks made by other people. Unfortunately though, widespread piracy means that many digital DJs aren’t paying for their music, and even when they do, it doesn’t generate much revenue for artists and labels – especially when online music stores generally keep at least 30% of the purchase price for themselves.
Source: How producers can get paid through streaming services