If you are doing something that has been done before, hire a realist. Your project will ship on time and within budget. If you are doing something that hasn't been done before, you need an optimist. Partly because the realists run for the hills -- they know the odds and the odds are bad -- but also because their hedging behavior will turn your small chance of success into zero chance of success. On these projects, optimism doesn't guarantee success, but pessimism/realism does guarantee failure.
So no, I am not scandalized to find that the world's biggest innovator (I hate his politics, but this is simply the truth) is systematically biased towards optimism. It's not surprising, it is inevitable.
Wright Brothers took a risk and build first planes but didn't have to lie that their planes already left the ground before they did.
They didn't claim "it would fly a year from now", they just build it over and over until it flew.
They were optimistic and yet they found a way to be optimistic without claiming anything untruthful.
Clément Ader, on the other hand, claimed that his innovation flew, and was ridiculed when he couldn't proof it.
One look at their works and it's clear who influenced modern planes, and who didn't.
The Wright Brothers are infamous for failing to industrialize their invention -- something that notoriously requires investors and hype. Perhaps they wouldn't have squandered their lead if they had been a bit more public with their hopes and dreams.
There is a difference between saying "we believe we will achieve X in the next year" and "we will achieve X in the next year." Each framing has its advantages and disadvantages, but it's hard to accuse the person who makes the former statement of lying.
The tenth time, you should have the good sense to realize that they're full of shit and either a habitual liar or utterly incompetent.