Oh that's easy to answer: they don't. That's why manga is growing.

There's always the gateway drug to anime and then manga, your Pokemon, Digimon, Yu Gi Oh if that's still going or just the reruns you can do because the amount of episodes. Back in the day, you still had comic book cartoons that were fantastic to guide them to the comics whereas manga had obstacles thanks to language barrier.

But with comics so shit nowadays, the comic book retailers that still exist have made the effort to transfer to manga making it easier to buy and collect removing the advantage the comics had over manga.