The country has negative interest rates. That money has to go to work somewhere.

SoftBank raised $100 billion (!!) for investment: https://techcrunch.com/2017/05/20/softbank-vision-fund-first.... It's no wonder that SoftBank seems like it participates in many startup funding rounds.

This seems like a bad idea - there are only so many good startups at any given moment to fund, so a lot of the money will go towards non-viable startups.