Being able to generate believable (but ultimately false) information at scale is a very powerful tool. Even when it is just humans with automation assistance it is already a massive problem, if it can be done completely hands off you can essentially drown out the signal and create an alternate online reality that will only look different to eye witnesses. And we're not that far from that. Being able to do something and being able to do that same thing at a different level of scale can be qualitatively different.
They're dumping billions of dollars into it because they see dollar signs at the end of the tunnel. Cost cutting, regardless of quality and ensuing enshittification. Stealing & laundering copyrighted works. Mass misinformation on a scale never seen before.
"Present birth certificate and touch heartbeat detector to log me in or else there's going to be a very large and very believable botnet dedicated to destroying your life."
I'm sure we'll come up with solutions like we did before. Worst case, "present birth certificate and touch heartbeat detector to log in"