Lying to oneself is called optimism bias. It means we imagine best-case scenarios and hope issues can be controlled, even as things go off the rails.
Lying to others is what leading scholar Bent Flyvbjerg calls strategic misrepresentation. Large projects sometimes incentivize fudging both the costs and the benefits, like giving overly sunny ridership projections for a transit project, in order to win public and political support.
Sarah-Joyce Battersby, “Why big infrastructure projects always go over budget — and what to do about it“, Ottawa Metro, March 21, 2017.
So “strategic” to know that what one says to others, or believes about self, is contrary to the facts. Less able to appreciate, when referenced to self? Though how much are “facts” a function of perception or context; at what point is one objectively lying?