Many good answers here, but I want to emphasize one particular facet: other experts help you become an expert. A thousand years ago, anyone could have invented

Many good answers here, but I want to emphasize one particular facet: other experts help you become an expert. A thousand years ago, anyone could have invented relatively basic math - but they didn't. The reason is that they didn't have other people to inspire and motivate and teach them. Very little knowledge comes ab initio or from a vacuum. Expertise is not created by working in isolation for decades. To build expertise, you need to be interacting with other experts. This doesn't mean they need to teach you, nor does it mean they need to be be in person. But you have to be at least reading what they write. It's much easier to reach the clouds if you stand on the shoulders of giants.