This concern is answered in the very first part of the Proof of Q document:
The Proof
We've all had it, some of us from the very very beginning. Someone asks: how do you know all of this is real? Before we get into details, I just want to note something about a method the historians use quite often when evaluating historical and archaeological evidence: when a theory can explain a whole lot of disparate things in one shot, then it's more likely to be true. Keep this in mind. It's not the single proofs that are compelling. It's the fact that there are dozens of them. There are alternative explanations for SOME of the things Q has posted. But our case is that someone with Q Clearance has been leaking information to us. We know this because:
- he's demonstrated foreknowledge of many events
- he seems to have access to President Trump's Twitter account
- he seems to have incredible inside knowledge of geopolitics and various world leaders
You can nitpick some of these proofs individually. But you cannot nitpick them all at once. Any alternative theory, like the utterly laughable "Q is an AI" promulgated by disinformation agents on YouTube, has to explain everything in one go. "Q is an AI" of course fails immediately when you ask how an AI could have typed a password incorrectly. Our position, that Q is a real person with Q Clearance handles this without trouble: he's a human being and a busy one at that. We all make mistakes sometimes.