That isn't really a thing. The 3% growth aligns closely with population growth (including immigration), and that's where it really comes from. If the average company makes widgets and the population grows by 3% then they hire 3% more people and sell 3% more widgets to 3% more customers, and the company is worth 3% more.
The unsustainable thing is really unlimited population growth, but steady state populations don't require some kind of cataclysm. They work a little differently, in particular people have to on average work longer before they retire because there are fewer working people to support them in retirement, but it's hardly mass starvation and nuclear war. And even the drawbacks are offset by things like automation -- not as good as both automation and population growth, but still probably not worse than your grandfather had it.
The real problem is that there is no iron law that says people have to spend their working hours on pie-growing activities like automation and honest medical research instead of pie-stealing activities like adtech and patent trolling, so if we have rules and institutions that make the latter more profitable, that's what we get.