Exponential growth.
There's a myth out there that we are unconstrained by physical resources. And it has largely been true "since the beginning of time". But that time is quickly coming to an end -- the next big generation shift will be the acceptance of a resource-constrained world imho.
Look at meat consumption. It takes something like 10x as much energy to grow a calorie of meat as it does a calorie of vegetables. If the entire world (or even just the global middle class, if something like that exists) ate as much meat as the developed world, it would be an ecological catastrophe growing all that livestock, disposing of its waste, and fertilizing the grain needed to feed it. And guess what, as the populations of India and China are entering the middle class, they're adopting a taste for meat-heavy diets.
Energy consumption per capita is a pretty good proxy for human development. Whether it's meat or our plastic lawn furniture that we consume from amazon, all of it takes energy to produce. In other words, consumption is another word for energy, and if even a sizable chunk of the world consumed as much as we do in the western world, it would require something like more energy than all proven oil reserves. Clearly that's not going to work.
We can always hope for the deus ex machina ending and say that we'll find salvation in technological progress (whether it's an efficient way to store solar or figuring out fusion or an FTL drive top open up new worlds), but that requires a dangerous amount of hope. It's also the path of inaction -- wait for someone else to deliver salvation.
More realistically, I think consumption is starting to hit physical resource constraints and is inflecting towards the top of the S-curve. The entire global economy since the beginning of time may have been about consuming, but that doesn't mean the party can continue.