Just like today's Internet. BGP spoofing, CALEA, DDoS.
> Access to it used to be highly restricted as well ...
And this is where the regression or "downfall" is beginning. Access to the Internet (as in ability to send/receive arbitrary data to the wider Internet) is something I bet is going to be increasingly restricted, but most people won't notice because they don't understand the difference between apps and the Internet.
I'd be surprised if direct access to the Internet is possible for consumers in the next 10 years. Everything will have to be through approved apps (age assurance is going to be the catalyst) that work over registered tunnels contracted through ISPs, if there isn't an outright blurring or merger between the concepts of phone/CPE, ISP and CDN. Your non-tech layperson will not know any difference whatsoever if all they use are their phone plan, streaming/banking apps and Facebook.