Why are authors going to stick with publishers in 10 years or 20 years or however long it takes for there to be more eBook purchasers than physical book purchas

Why are authors going to stick with publishers in 10 years or 20 years or however long it takes for there to be more eBook purchasers than physical book purchasers? I mean, it only took cell phones what, 15 years before they were so common that people in third world nations had them, right?