The internet is not decentralized the way Bitcoin is. Actually I'd argue that the internet is more like the modern banking system: you have big corporations (ISPs, Google, Facebook, Netflix, Amazon...) interconnecting to provide a service to users in exchange for money. They have a vested interest in making sure the network actually works, at least for them. If you want to use the Visa payment system you need a bank account, if you want an internet connection you need an ISP. Bitcoin has nothing like that.
What will be bitcoin's "ISPs"? Who makes sure the graph remains connected and usable? Who invests in the "infrastructure", making sure channels remain well balanced? Some say that Lightning will be self-balancing through a clever set of incentives, but that's again extremely experimental and untested.
Also note the big "net neutrality" thing going on in the US right now. What will prevent big players from teaming up and interconnecting with each other to facilitate transactions while leaving out the rest?
I don't have the answers to any of these questions, maybe it's just FUD. I'm just surprised that bitcoin is a couple of weeks from making such a huge jump into the unknown. It's extremely interesting to be sure, but I feel like some people are going to get severely hurt if this whole thing comes crashing down.