2. Warren Buffett invests in businesses, not in non-productive assets(e.g. gold, bitcoin, silver, etc)
3. Warren Buffett invested in a gold mining business that generates cash flow, not in gold specifically
Let me play devil's advocate for a moment.
If Buffett can wrap his mind around ROI on a gold mining business, what is to stop him from seeing the exact same value proposition on a BTC mining business?
I don't see him hoarding gold or BTC, but mining infrastructure also plays a role in price discovery. Not to mention the legitimizing effect such an investment could have on the mainstream investment community!