30 % of the population consuming 40 % of the resources isn't a big deal at all. And even if it was, is there any reliable manner in which we can measure these "world resources" or is it just commie conjecture based solely on standardized monetary value?
Numbers that are a rough estimation, very conservative estimations though. But yes, there are 'reliable' ways in how to measure it. But even if you could not, if you just use your own logic, reasoning and common sense you should at some point come to the realisation that we are living in a world with limits. This planet might be fucking huge, but it is after all, a physical object. That means the number of resources you can squeze out of it, are also limited. And a growing population with a growing demand, will at some point run into said limitations. Does it matter if we hit them in 100 or 500 years?
Preservation and taking care of your environment, for your own sake and those of future generations is a good thing.
https://www.theguardian.com/science/2005/mar/30/environment.research
There is a lot of research about this subject. And while the details might sometimes be a bit different, the message is always the same. This planet can not support a limitless amount of humans.
However, I don't claim to be an expert, but you could make it a very basic game of math, really. And everyone who was in grade school, should be capable to figure it out.
I am not going to look up the numbers for now, simply because I am lazy as fuck, but it's not about the numbers anway, but the idea behind it.
For example, go and look up how much nutrition a human needs, just to survive. Now look at the best sources for it, be it mushrooms, meat, or what ever. And then look at the resources it takes to get those. And then see how much the planet can provide you with said resources, be it space for agriculture, transporation, storage what ever. And now you know the bare minimum of how many humans our planet can sustain, in the most ideal condition. - which brings us to the next point, ideal conditions can not be achieved.
Could the ideal number be 20 billion? Or 25 billion humans? What do I know, like I said it is not about the numbers here. But what I know, it's not limitless. Now a human needs a lot more then 'just' food, most humans also need shelter, clothes, and most probably something for entertainment would be also nice.
And the number of how many humans this planet can support, is already shrinking. By a lot.
This is really not rocket science. And if you can believe most scientists, it seems we are nearing this tipping point, where the planet won't be capable of supporting humanity anymore at this rate. At least if we factor in our current standar of living, with all the overproduction and overconsumption.
Now, since creating a new habitable planet is out of the question - at least for some time, there is pretty much only one realistic option left. Changing our habits. Because it is very unlikely that someone will find a way to multiply the resources of our planet. Even if we are 100% efficient with EVERY resource there is, which is impossible anyway, we will STILL hit a limit at some point. Another way, could be also to cut humanity in half ... I guess ... and who knows, this might happen as well. World War 3 maybe? A very huge famine? Natural disaster? We will see. Maybe in 150 years when like 4 billion people died, we will do some serious changes, like, yeah, we tried this capitalism thingy for 200 years, and yeah it didn't really work that well, we should try to avoid it in the future.
And even if this was true, why should we care? Are we not the ones benefiting from this?
I am in my 30s now. Sure, why the fuck should I care what happens in 70 years? I most likely will be dead by that point, or well close to death. But if you ever want to have children, and grand children, well and as Hassknecht said, basic empathy, foresight and such, then it should at least make you think.
On the other side, a certain amount of self preservation is a very healthy thing. You should try to conserve resources for the same reason as why you don't push your body always to 120% of what it can deal with. Besides, the world will not simply colapse from one day to the next. It is a gradual process. Some of the issues will hit us in 25, 50, 70 and well 100 years from now.
Polution from China, is already detectable in Europe and the US, raising see levels will affect people in Venice, Italy in the next 50 years, the garbage trail in the ocean will grow and affect more people and so on.
I take it that you're younger then I am - just a guess - so that means you will eventually have to face more of those effects than I do. So you should have a very keen interest at least in your own future.
You could as well ask, why you don't shoot your self in the own foot. Logic, I guess?