Transistor current calculation
The NPN transistor in your circuit needs about 0.6V across B-E before any significant amount of current will flow through that junction,

As such there needs to be at minimum about 600uA flowing through that resistor to reach that voltage,

Once your past that point, the B-E junction still has a voltage vs current curve, so there is some point where the amount of current the B-E junction is taking in, and the resistor drop the same voltage, for you this happens to be at 250uA flowing into the base, with a junction voltage of 0.623V,