About EU real users instagram cookie

Is it really possible for someone to get this many cookies every day? Where can I actually find people like that?

That's absolutely true. People who collect thousands or tens of thousands of cookies/accounts every day usually don't do it manually, but use automated systems.

I think it depends on the source. Getting a few real user sessions is possible, but huge daily numbers are harder to verify.

It would depend on the definition of cookie as well as the application context. When referring to browser or user accounts, obtaining them from random individuals would be associated with problems related to quality, security, and compliance. It is better to create your own source through your own users.