Judgment, when applied to personal habits, may be used to assure that one’s own self-image remains intact. That is to say that judging the behavior of another as of lesser quality than your own may bolster a self-image of superiority. Beyond that, judgment likely provides little if any value.

Regarding the question of from where the “right to judge” arises, it is a personal choice and thus requires no special right or authority to use.

As my experience, to enjoy a vegan lifestyle or not is also a personal choice. In my case, being vegan is informed by and supports my personal commitment to live joyfully and healthily while causing the least harm I can to the beings with whom I share the planet. It is easy for me to imagine that each person with whom I meet is living in a similar alignment with their unique commitments. Likely those commitments are different than mine, but certainly not of lesser value to them. Thus there is no room for judgment of the behavior that arises from the pursuit of those goals.

Spread the Vegan message gently. Live as an example of the results that living a healthier, lighter more intentional life delivers. Few, if any one is interested in a life of judgment and condimnation of others.