What would attract ants into the attic?

Ants appear to be entering the attic space through a vent beneath the peak of the roof.

There’s no large stream or ribbon, just a scanty but fairly consistent trail visible externally.

There’s no sign of ants in the rooms beneath that part of the house, which include living room and kitchen. (There’s no evidence of ants anywhere in the house.)

Access to the attic from inside is a challenge. No one goes up there. Nothing is stored there. It’s just a space with insulation foam in it.

The question is: how likely is it that there’s something going on up there that we should take pains to investigate or hire a professional to inspect?

A few ants coming and going aren’t a big problem as long as they stay out of our living space. There are ants all over this property, and we haven’t had a problem inside the house in many years.

Is this something we can ignore or not?