The carbon sequestered in the earth in the form of coal, oil and gas hasn’t always been in the earth. After all, hydro carbons are in fact hundreds of millions of years of dead trees buried under mud sequestering atmospheric CO2. Which implies there was a time with all that CO2 in the air yet still trees to capture it. By releasing it all, we reset the biosphere’s clock to about a time when earth supported a different kind of life (one without us in it), but life nonetheless.
Frankly, the comparisons to Mars and Venus seem a bit overblown.
If we don’t learn, then WTF are we doing with ourselves. The human existence is the pursuit of knowledge. The only depressing thing here, IMO, is the idea that living out a life as grazing cattle, concerned with nothing more than gorging oneself with the next meal is the only reason to live.
Comfortable? Sure. Self-actualized? Not a chance. There’s more to life than living out only the most basic biological needs.