The most common argument used in defense of mass surveillance is ‘If you have nothing to hide, you have nothing to fear’. Try saying that to women in the US states where abortion has suddenly become illegal. Say it to investigative journalists in authoritarian countries. Saying ‘I have nothing to hide’ means you stop caring about anyone fighting for their freedom. And one day, you might be one of them.
You’re right, nobody can ever know even remotely everything.
Luckily, the same device you used to post that comment can also be used to check if what you are about to say is actually true, so you can prevent yourself from spreading misinformation like this in the future.