That you called it a "steep discount" is why. Imagine that the market optimal price for the plain service is $70 and the amount they could monetize from persona

That you called it a "steep discount" is why. Imagine that the market optimal price for the plain service is $70 and the amount they could monetize from personal data is $2 a month. By offering the $100 tier, most people are going to think "Wow, $30 discount per month! That's a great savings" and a small percentage of die hard privacy advocates are going to buy the $100 plan on pure principle, leading to basically all profit from Comcast. Note, in this scheme, the $2 a month extra Comcast gets from selling your user data is basically irrelevant. They could actually just do nothing with your data and still come out ahead. It's the pricing psychology game that's important.