The problem isn't really with the internet, but a handful of websites that have come to mediate the internet for a lot of people (despite appearances to the contrary, the two are not the same).
This is a critical distinction, because the former is a problem like "the water is too wet", like you can't really fix that. You can build new digital infrastructure though. That's a solvable problem.
And then that new infrastructure will be subverted just as the current one has been. I don't think this is an issue that can be solved through engineering. I think the problem lies in different domain.
Can't we just build a new infrastructure at that point? The current infrastructure worked well for about a decade. If we have to rebuild every decade then that's not so bad.
This is a critical distinction, because the former is a problem like "the water is too wet", like you can't really fix that. You can build new digital infrastructure though. That's a solvable problem.