Why do stars are visible in the same size in sky at some distance eventhough they are originally situated millions of light years away?

1. stars "millions" of light-years away are quite invisable to the naked eye.

2. even stars a few light-years away are so "small" (they take up such a small part of your visual field) that they appear to be dimenionless dots:

that is, they have location, but not size.