i. Some proportion of anyone’s beliefs are held because they meet emotional or psychological needs, not because they are useful or true.
ii. Some proportion of believers will hold beliefs for their whole lifetime, no matter what external evidence is presented to discredit or disprove those beliefs.
iii. Any belief which is widespread enough for you to have even noticed it is believed by a large number of people.
Lemma: For any belief, no matter how odd or silly or untrue or annoying you find it, an appreciable number of people will hold that belief for their entire lives.
iv. For a currently widespread belief is to die out in your lifetime, two things must happen:
a. your remaining lifespan must contain the point in time at which all the believers of that belief will have died, and
b. no new believers can be recruited to the belief during that time.
v. The chances of both iv.a and iv.b happening for any belief are very, very small.
Conclusion: Any beliefs of which you are now aware are going to be around for the rest of your life, no matter what happens in the meantime to disprove them, and no matter how much they annoy you.
Corollary: The Internet means that even if a belief be held by only a single person on a different continent, you will still be apprised of it.