Short-term stock price changes are noise.

Berkshire's investments are based on a deep understanding of the business and are intended to produce good long-term results. Factors like economic moat, trends in consumption, conservative valuation, etc.

For example, Berkshire purchased Apple (AAPL) between 2016 and 2018, at an average price of $35 per share (P/E ratio of 12 or 13), and it was years before that paid off. The Redditors buy during those years, before the payoff.

Berkshire doesn't have to be right about every stock pick as long as the average is good. But if you buy 100% of the Berkshire picks that go down and less than 100% of the picks that go up (because some never drop below the level they bought them for), there is a real risk that you could do substantially worse

Buffett makes huge new investments very, very rarely. Three in the last 5 years.

Apple: buying began in 2016.

The 5 major Japanese trading houses (the sogo sosha -- Itochu, etc.): buying began in early 2019.

Verizon: buying began in late 2020.

They all trade at or near Berkshire's price, if not far below, and you get one new idea every few years.

There are other new purchases (Chevron, Kroger, AbbVie, Aon, RH, etc.), but these are small, lower-confidence positions that are often sold as soon as the price rises far enough. Probably Weschler and Combs, not Buffett.