One of Buffett's investment principles is to only invest in stocks within his "circle of competence." If he doesn't understand it, he won't invest.

But if you stick rigidly to this principle, how do you make progress?

The first way is to continuously learn and research, to gain an understanding of other companies/assets, thereby expanding your circle of competence. As your circle expands outward, you can invest in relevant assets that now fall within the "circle."

The second is that companies themselves may change and enter your strike zone. For example, after the rise of mobile internet, Apple evolved from a pure technology company into a consumer goods company with a strong moat. This is similar to Buffett's logic for investing in Coca-Cola, which is why from 2016 to 2022, Buffett made Apple the largest holding in Berkshire Hathaway's portfolio.