No offense intended, but I think you don't understand the meaning of lucky or of trained.
You provided several paragraphs explaining how you recognized the threat, how you knew how to position yourself, how you assessed the area to gain an advantage, how you timed your strike, etc. It was anything but lucky and while you may not have
formal training, you certainly have a good deal of experience and definitely knew how to use the training you have gained in other areas to best effect.
Which gets back to the point that was made--not everyone has the tools that you have that would allow them to successfully solve a confrontation physically.