Idk, there are still people that study ants. Both professionally and as a hobby. Just because you don't care doesn't mean someone doesn't. I don't know why the same wouldn't be true for aliens. Unless those aliens are ant like (hive mind...ish)
What percentage of ants that exist are studied? They absolutely study some, but the vast majority of ants won't ever be acknowledged by a human. That seems like a relevant factor here if the assumption is that humans are like ants in both interest level and commonality in the universe.
Not to mention there are endless number of nature documentaries on Ants. If ants were not interesting then the National Geographic channel wouldn't have ant documentaries as often as they do.
I'm not sure I like this line of reasoning because it implies that the ants aren't aware of us. Certainly they are in some cases. Ants are able to physically perceive us. So if aliens aren't using some means of passive remote sensing to study us then I don't see why we wouldn't also notice them (though they may have good reason to not use active means). Sure, the ants aren't aware of what why we're hanging out around them, but they are aware of us.
The topic was really about how we may not know we're being studied by unknown aliens, just like ants. My response was about the ants not knowing the why but still aware of existence. So far we don't know about the existence of aliens, hence the part about how they'd have to be doing passive and remote studying.
When you live to be a billion, you probably study ants just to have something better to do than bitch about joint pain.
And having seen many, many, many ant hills, specific ones with slight odd variations unnoticed by people who are merely a million years old would stand out like a flashing neon sign and you would be all "Hello! What, pray tell, is this?!" while everyone looked at you funny because they lack context.