Maybe some of them. The others only have one or two seasons, if that, because the network/studio/whatever is all about a quick buck and not actually seeing the story through properly. By the time one is aired or streaming, they've already got their eye on the next one.

You also have to have good writers who see more than just the starting content. Look at Rogue One>Andor, all born from taking a single line at the start of a movie and asking, what happened there?