Damn! That computes to 671,000,000 mph! But what is the reason for the speed of light to be exactly that figure and not a bit faster nor slower

And what happens to that number when an object is speeding away from you at 20,000 mph ? Or towards you at 20,000 ?
What prevents the speed of light from speeding up or slowing down? And when that light leaves an object, does it start slow and gradually reach 186,282 or does it jump to that speed immediately?
Johnny, it really is time for you to read "Dancing Wu Li Masters" .... the easiest study of Quantum Mechanics presently available.
A slight understanding of QM will blown your mind!
Get that book and read one chapter a night and then think about it as you fall asleep.
It will change your life forever!
Or maybe start with a general knowledge of the theory of relativity. Understanding relativity first kind of helps with a better understanding of QM.