Lets say I spend $150 for a really good device that I have complete control over, using your $10/month rental fee, mine is free after 15 months, you are still paying for yours. After 30 months (2.5 years) you have paid twice as much as I did. Of course, your numbers might be different, but I doubt they are better. BTW it is never free, maybe the cost is bundled into your other services, but if you believe its free, then I have a bridge to sell.
It must be that new math that millennials are being taught to say that makes sense.
Also, do you realize that if you buy a really good access point you can cover a 3000 sq ft home with one access point. And your own device will work just fine when you move or transition to another cable company or ISP.
It used to be that the tech improved so much that it was outdated in a couple of years, but now that is not the case. But even back when it was the case, the cable company would not replace your outdated hardware without a lot of work and effort on your part.
This does not even start to talk about the quality, which Comcast spends dearly on to get good reviews. But if you compare Comcasts devices to well designed devices you'll see that they cut corners to get the cost as low as possible and the profit as high as possible. Try reading about buffer bloat sometime,
XB6 Buffer Bloat Link or the other terrible design decisions made in low cost consumer end points.
It is a shame that critical thinking has reached such a low point these days.