1. Net neutrality places severe binding restrictions on how internet service is provided, and by extension who can provide it. (It's expensive to serve up Netflix if you're banned from offering Netflix privileged pipeline status. It's harder to start a new ISP when any internet service has to follow strict neutrality regulation.)

2. Once it is cheaper and easier to provide internet service, you can expect to see costs fall as the market becomes more competitive as new players enter the market and established players invest in optimizing their infrastructure.

This is the basic argument offered by Pai and other deregulation proponents. And the market doesn't have to be perfectly competitive for this to work out. I have three cable ISP options where I live so I'm not worried.