The idea that we all have to work the hours that we do, for us all to live comfortably, is the original claim here. One that you seen to back and demand sufficient evidence, to your own personal standard of burden and quality, or it must be 100% true, even if it definitely sounds like a lie rich people would make up to trick you into working for their profit.

Source: WW2. People don't really take in how much of the world was at war in WW2. Appart from the obvious, the civil war in China and the millions of indians conscripted made the numbers of human men fighting, per percent of the population, huge. Yet, despite this, they had enough bullets, aircraft, ships etc. to literally fight a world war. Something like 3 tonnes of ammo was shot per soldier killed: insane production levels.

More so, outside of of deliberate action, callousness and or incompetence, there was more than enough food produced and no one staved.

If we could do that then, why couldn't we do that even better now?

Unless you have a source that we do need to work 80% of the hours we're awake as an adult, just to keep the world from grinding to a hault and us all dying of starvation and you weren't just going to point at the planet and go "see, were not all dead" you got the source you deserve.