The hyperexplosive growth of all tech (startups AND enterprise) in the period might be the big explanation. As to what explained that, possibly the chief factor

The hyperexplosive growth of all tech (startups AND enterprise) in the period might be the big explanation. As to what explained that, possibly the chief factor was low interest rates, with other factors being Covid-led digitalization, growin demand for some hot sectors like crypto, fintech, AI, etc.