I assure you even if we were to continue in our current trajectory the Earth would support human life for more than two lifetimes.
This is not to say that we shouldn't stop wasting, but let's not exaggerate. That being said the Earth definitely will become less comfortable if we don't put a pin on some of this stuff.
Conversely, were the global economy collapse completely, Earth will barely support human life for even one lifetime.
Obligatory reminder: unless you're Sentinelese, it's highly unlikely you or your community is actually self-sufficient. For most people, everything they eat, everything they wear, everything they live in and live with, is a product of, or is directly dependent on, international manufacturing and shipping. If that goes, billions of people starve.
This is not to say that we shouldn't stop wasting, but let's not exaggerate. That being said the Earth definitely will become less comfortable if we don't put a pin on some of this stuff.