1.) You should read up on what it really means to have "true rationality". Here's the thing, we don't omit the possibility that the individual will never understand what "true rationality" is, in fact Bayes' Theorem shows that it's impossible to assign a probability of 1.0 to any theory of anything (never mind rationality). You can't argue with math.

2.) Yes, all of your goals should be approached with caution, just like all of your plans. We're not perfectly rational beings, that's why we try to become stronger. However, we approach things with due caution. If something is our best course of action given the amount of information we have, we should take it.

Also remember, you're allowed to plan for more than one eventuality, that's why we use probabilities and Bayes’ theorem it order to work out what eventualities we should plan for.