It's important to understand that SoftBank is no ordinary bank; while it had been a reasonably successful bank, the distortion truly began with the Saudi government turning up and asking them to invest $200bn for them.

There simply isn't $200bn of real positive capturable return investment opportunities out there available at once. Anything physical would be hopelessly bottlenecked by its own size and would be unable to scale rapidly enough for the investors. So it had to be thrown at all these hugely speculative projects with the goal of capturing entire markets.

The real problem is that, due to a century of fossil fuel dependence, there's a huge amount of wealth concentrated in weird desert monarchies.

SoftBank was never a bank. It was a software company that turned into a cellular provider.

This. The disease is gross wealth inequality that leads to a certain sector of society having to figure out where to put all that money while the bottom 99.99% are facing real problems.