We see in this thread on full display that some are satisfied to rely on reference books, formulae, and theory that can be assessed, studied, and evaluated from the safe, protected, comfortable environment of an office or home, completely avoiding the risk, hazards, and unexpected consequences that may arise, result, or derive from actual experience in the real world. Acting in that way means one will never have to question their "beliefs" which of course are not their beliefs but that of others but it is easy to feel safe, expert, and knowledgeable in such conditions. You can see in this thread that when exposed to data, experience, and knowledge out side of their protected world that raw emotion, bad logic and insults result because they feel threatened or their ego bruised.