Umm wow. Who wouldn't see a benefit of owning your own cable modem. Actually when I first bought my moto 5100 at best buy in 2002, they offered a full 69.99 rebate which made it free. I've had that same modem since 2002 and still currently use it without EVER having issues with it. That's 7 years of consistent service and counting. If I would have rented, 5*12=60*7= $420. LOL yeah renting is definitely NOT the way to go. Those who get failed modems most likely do not have them plugged into an APC battery backup or have the cable wire surged before plugged into the modem. Simple precautions and measures such as these will keep it going strong. -- If it ain't broke, don't fix it. Unless you know what you're doing.
I wouldn't. Cablevision charges - $0 - to rent a modem. When mine dies or I get tired of looking at it I can bring it to any walk in center and replace it.
Now the remote control for my DVR - They charge me rent on. I own a Logitech Harmony, though. I keep the DVR remote in the car and occasionally swap it out for a new one (free AA's!)