Advertising provides recurring long-term income that far exceeds the amount you're prepared to pay for most devices. Each individual online across all devices

Advertising provides recurring long-term income that far exceeds the amount you're prepared to pay for most devices. Each individual online across all devices is worth about $200/year in advertising revenue ($200bn in global revenue over about a billion individuals). Take a share of that every year and you end up making more than you would have made on the device sale without that.