I think the question is poorly phrased. The question would rather have to be: why aren't many people buying bitcoin? Years ago it made sense to think that bitcoin was going to disappear or go to 0, things like that. But if companies are buying en masse it's not just because they think it's the best financial asset in the world, it's because the regulatory issue is clear and they see that there's no going back.

If you are a retail investor and you are not buying bitcoin, or you have bought some and sold it when it went down because of Iran, things like that, maybe you have to consider changing your strategy.