Understanding the biasing of a transistor with negative feedback
The reasoning goes a bit like in circles. The more base current flows, the more collector current flows. The more collector current flows, it brings down collector voltage, and it reduces base current. So there is an equilibrium where voltages and currents are stable, so just the right amount of base current is in balance with just the right amount of collector current.
The collector current is roughly 100 to 400 times the base current, as shown in the image. Transistors have quite large manufacturing tolerances regarding the current gain.