> I just assume I'm not interested enough to be spied upon by randoms
I believe the fewest are. But constant surveillance is an advantage if you need to monitor general opinions or if they find you interesting at a later point and want to check your history.
So if you talk about burning wood in your stove a lot and it later becomes illegal you might have a hard time denying you have a stove if they ask you to pay extra carbon emission taxes.
Or if you talk about chest pain a lot and later want to get a new health insurance you might find that your options are mysteriously more expensive than others.