Some people are bitten by bug of optimism. This is because they occupy the higher echelons of hierarchy in some organization. This bug bites them and they want to impress it upon the subordinates to be optimist and do the work sincerely and without any questions about the veracity of their projects.
In different religions of the world, every concept has two counterparts. Nature abounds in complements. Man and woman, Yin and Yang, Shiva and Shakti. So much so that Shiva took the form of half man-half woman to show that one is not complete without the other. The life propagates through the complements. A Car cannot run on one wheel.
Also, there is law of conservation for everything. I surmise that not only matter, energy, momentum follow these laws, happiness-sadness, optimism-pessimism also follows these fundamental laws. By this logic, when you talk of making many people optimistic, at the same time you are making equal number of them pessimistic. As positive charges cannot live alone, north pole and south pole of magnet cannot exist separately, optimism cannot exist alone.
So, don’t be lured by such attitude. Do your work sincerely without the need of any advice. Oh! I am also becoming a pedagogue.