I hear that every now and again, mostly from people who are ignorant of how much there is to know.  “All it takes to be a farrier is a strong back and a weak mind.”   Oooh, my favorite is “it’s not rocket science!”  That’s right, it’s not, you can stab a rocket with a nail and it won’t kick you head in.  Horseshoeing is however a medical field.  Especially my branch of expertise.  In aerospace if you manufacture a part wrong, QA catches it and no harm done.  Though mostly no one is checking my work for mistakes besides me.