My take on the conspiracy theory issue:

There are certain mental illnesses which make people more susceptible and prone to conspiracy theories. For most of history these people were largely isolated and spread randomly throughout various communities. This had a moderating effect, as contact with non conspiracy people didn’t fuel their theories as much.

Fast forward to the internet as a tool for finding and building communities, and conspiracy theorists take advantage of the new technology to find each other and form larger communities of conspiracy theories.

Finally, recognizing a new political constituency, the Republicans decide to start messaging directly to these conspiracy theorists. Their goal is to undermine and dismantle the government, and so they see government-suspicious conspiracy theorists as a natural constituency.

They will not stop as long as the conspiracy theorists continue to eat it up.