Pepper spray is just another tool. Having pepper spray on your person does not mean you must go to that first if you are being threatened with serious physical harm or a lethal threat. Depending on the level of the threat being used against you, pepper spray will give you a tool to use if you are being threatened with less than lethal force or of serious physical harm. I also believe it is certainly preferable to drawing a firearm (because that is all you have) to try and dissuade a perceived threat. It sure beats being on the receiving end of a physical assault that has not escalated to something more serious and it MAY open up an avenue of escape or time to react in some other way.

Perhaps a review of the Dept of Justice's "Use of force Continuum" would be informative. While it normally is applied to law enforcement use of force, it is advisable for every armed citizen to be aware of it also.

The Use-of-Force Continuum | National Institute of Justice