Why shouldn't I switch internet service?

Looks like I can save $70 a month, does Cox have any plan to compete with this?

I have T-Mobile cell phone (used to have Sprint), so why shouldn't I switch internet service?

"What’s even more interesting is that T-Mobile is treating its 5G Home Internet just like another line on its Magenta Max family plan, so users who already subscribe to T-Mobile’s wireless phone services can get home internet for only $30 per month.

The Un-carrier will also be offering its T-Mobile Tuesdays incentives to broadband customers. Starting next Tuesday, May 10, T-Mobile will kick off the program with a $50 discount on any streaming device to make it even easier for folks to ditch their internet and TV bundles."

https://www.digitaltrends.com/mobile/t-mobile-wants-you-to-test-drive-its-5g-home-internet/#:~:text=What%E2%80%99s%20even%20more%20interesting%20is%20that%20T%2DMobile%20is%20treating%20its%205G%20Home%20Internet%20just%20like%20another%20line%20on%20its%20Magenta%20Max%20family%20plan%2C%20so%20users%20who%20already%20subscribe%20to%20T%2DMobile%E2%80%99s%20wireless%20phone%20services%20can%20get%20home%20internet%20for%20only%20%2430%20per%20month

Thanks for your advice.