If you are the record label who owns Lady Gaga, and you have a new artist coming up, you can say, 'Let's have the artist play just before Gaga.' Now you've exposed the huge Gaga audience to the new artist. It's similar to showing a trailer before a movie. The hit creates a hit.
Think about trailers you see in theaters. If you're seeing a Warner Bros film, the studio might have three of the five trailers. So having a hit helps you create the next hit.
Most large media firms make outsized investments to acquire and market a small number of titles with strong hit potential, and bank on their sales to make up for middling performance in the rest of their catalogs.