You sound close minded.
It's no different than actors distributing movies through their own production studio. Why do that when they can just keep starring in movies with a big studio and stay cashing checks? Yet they do it.
How many actors stop acting in movies all together so they can do nothing but produce? DiCaprio has his own production company but he acts in other films outside of that company. So your analogy makes no sense, it would be like saying OK, Lonzo Ball is gonna wear BBB but he also has a side contract with Adidas where he wears their shyt for road games and BBB for home games

Aside from that -- in your movie scenario, most movies have several different production companies behind it and a producer or production company rarely if ever funds an entire movie. They might put in a little, but movies are financed by many different sources, including private investors, banks or the distribution company itself. Who is gonna fund BBB? Probably Lonzo himself.
Not to mention the fact that the sneaker business is a lot more difficult to break into than film or music. Hundreds of films and thousands of songs are released every year and every year there's new films, new actors, new directors having success. In shoes, one company holds 90% of the market share in basketball and over half the market share in general apparel (while 2 others account for the majority of the rest) so its nearly impossible to break into. Only a complete dumbass would try to compare these two businesses
