Bizarre question ( if taken seriously).
Video games give you direct, visual and audio presentation of everything you do in campaign/world: you're not imagining things, you see everything with your own eyes ( from customization, combat, world, characters, etc). It is a more "narrow", far ( far) more controlled/predictable experience, but also far more immersive. Add to this the art, music, writing, etc.
Same reason open world games today are hugely popular: we have the tech today for it, to take it even further.
And now some nerd will probably step on the soapbox and say:
"Muh imagination! I can do all of it, with muh imagination!"
To hell with it.
Few people ( usually either a genius or a complete lunatic) can create worlds in vivid detail, a la Tolkien.
PnP still have their place ( and their own type of fun), but it requires a lot more setup and commitment for it.