The 2021 Berkshire Hathaway Annual Shareholder Meeting is on Yahoo Finance. For those uninterested in SEC filings, annual reports and the likes, or like me are without financial wiz/acumen/moat, Buffett recommends buying the S&P 500 Index fund, and staying put.
He shows the zero overlap between the largest 20 companies now and in 1989 (30 years ago) to make his point. By owning an S&P 500 index fund, you’re basically ensuring the next 20 largest companies are in your portfolio 30 years on (or actually, at every given point in time).
On a personal note, our own portfolio has an all in tilt on US stocks, and while we’ve benefited from that, there’s no telling what the geographic make up of the next largest companies will come from. 
Jack Ryan shares a similar view, if you need more validation.