There are several factors at work chief among them is the simple lack of awareness. While most people are somewhat aware that the amount of energy we currently use is unsustainable most people have not done the maths to prove that is so. As a result people are not only more easily swayed by unrealistic claims made from pro renewable or nuclear energy groups they also do not know the magnitude of overshoot we are in. If there was a greater appreciation of the amount of energy we gain with fossil fuels then perhaps there would be a bigger push towards a more sustainable lifestyle.
The other big reason is there is a normalcy bias which results from the fact that man has always increased his energy usage year after year and since this trend has occurred for a long-period of time it is assumed this trend can carry on indefinitely. This incorrect assumption also fits into the meme of social progress and unlimited human innovation where man has always transcended resource/energy scarcity through sheer intellectual brilliance. As people often say:
"The stone age didn't end because man ran out of rocks so the oil age won't end for the same reasons."
This on-going trend in energy usage - and the subsequent incorrect assumptions that rise from it - is not limited to energy use. For a long time house prices rose in the US and it was assumed that this trend would continue forever. This trend of rising house prices had only been around for 50-70 years so we can see how easily these believes can take hold. However the energy trend has gone on much longer so it will take a lot greater shock for people to reassess these assumptions. It is this reason why I think the vast majority of people still believe we will get out of this recession despite all the evidence to the contrary as there is a lot of inertia between what we think in our minds and the physical realities we keep seeing.
Other secondary reasons come from the fact there are many elites who benefit from the current status quo. Revealing the truth would be an admission that this paradigm is not only unsustainable but it is also wrong which is a greatly damaging to the ego and reputation of the people in power. More important however this admission could be a threat to ones power and it is quite likely that if J6P really discovered the truth there would be widespread panic and revolution. After all if there is not enough energy or resources for everyone then people will fight for their survival and will look to scapegoats to blame for this mess. Best to keep the masses ignorant with misinformation and distractions. My list is by no means exhaustive and I am sure other posters could highlight other reasons but I feel the ones I highlighted are the main reasons.