Not because he is economist and wealthy person you are going to believe on him. He is not into digital investments and more on physical and tangible investments, meaning he believe on what he only sees unlike on cryptocurrency the ability to change in value is on a deeper aspect where the interpreter is only the graph. Bubble may blow or may land on a water surface that will last long enough to be recognize.
Not only that, he's an old school trader that love tired out and known markets and this digital is something new to him. But even him realizez the potential of exploring it's volatility. If they wanted they could easily control it by poring 100billion in btc. I think that that already happened when the likes of him got out of BTC when it reached 20k.