This is at least partially biological. We are competitive because our survival depends on it, and deception is of utmost value in a competitive environment. See all of Capitalism, for example.
>We are competitive because our survival depends on it
Says who? Our survival, as does the survival of almost all life, actually depends on Cooperation. I'd highly recommend checking out the book Mutual Aid: A Factor of Evolution by Pyotr Kropotkin. You can find it for free online (legally, its public domain) https://gutenberg.org/ebooks/4341 .
This is good context but isn’t a justification. You didn’t say it was but I wanted to emphasize that a biological reason isn’t a moral justification.
> deception is of utmost value in a competitive environment
All lying is deception, but not all deception is lying in the sense I intended. I make the distinction because camouflage, wood patterned linoleum, or mental reservation (outside oaths and other serious matters) are all forms of deception but are not lies.
> See all of Capitalism, for example
Don’t conflate capitalism with Marketing! It isn’t unfair to characterize marketing as weaponized lying. Selling my beets at the farmers market is capitalism but is not lying.
>Selling my beets at the farmers market is capitalism
No. It is not. People have been selling their wares at markets for thousands of years. Capitalism has only been around for about 500 years.
Capitalism is a system of economics where the means of production (Capital Goods) are owned privately by the owning class (The Capitalist). It's a relationship between the owner class, and the worker class. Owning the farm and employing workers would be Capitalist. Selling wares to a market is just commerce/trading.