Yes, encourage dreams even if they do not best utilize talents
No, encourage allocation of talents even if they are not their dreams
Talent isn't everything. Motivation is a huge factor too
Yes, but people should be aware that their medieval studies PhD. probably won't land them a job.
They're dream will change, and they should learn many talents, but let me be clear. you are to blame if it doesnt work out
Human progress is made only because of those who dare to be wishful. Should a child's imagination, creativity, genius be suppressed just so that he or she can be crafted into another worker bee? I think not. Because dreaming is motivating, and motivation, if anything, is what drives society forward. But I extend the following caveat: you cannot achieve your dreams if you sit on your haunches and stare up at the ceiling--this kind of passive wistful day-dreaming could at best give you a sensation, an illusion of success. If one wants success, seize every opportunity, every chance to advance one's agenda.
Dreams can come true! Even if it's unrealistic, let them dream! If no one dreamt, the world would be a dull place. You should definitely not tell them it won't happen because they won't have confidence in themselves and you never know, if they work hard enough, their dream may come true. If it's not going to happen, they'll find out when they're older and more mature, so let them find out for themselves.
This should be the way to go, unless they really, really hate their talents, which is unlikely. They can still pursue those dreams as hobbies.
People need to do what they can make money at.