The Vision fund was never really about funding breakthrough technology but instead moving the Saudi's economy away from a dependence on oil.
That aside, when you have $100B investing it is actually quite challenging. Take Stripe, for example, a fantastic private company that is valued at over $33B, but it has raised drastically less money than Uber or WeWork.
In order to deploy $100B it isn't enough to make $300MM bets because it would require 333 such investments. Just imagine. You would need 330 companies the size of Stripe and lead a late stage growth round to deploy that amount of capital.
Now Stripe has raised less money because they are more capital efficient and aren't burning cash like Uber or WeWork.
With Uber, at least there was a game plan because it was a tech company. Now it isn't important to debate how much of a "tech" company Uber is, simply think of tech as leverage. Which is the basic idea of tech companies, meaning that you write code once and then you can infinitely replicate at a near zero cost. While building something physical, your cost doesn't decrease towards this zero amount.
People also thought that DST was crazy when they invested at Facebook at a $10B valuation, but that has worked out well for them.
So regardless, Uber was a good investment and worth the risk, and still we have to wait and see where Uber is trading in 2-3 years time.
The real problem for the Vision fund is that to deploy this capital they necessarily need money losing businesses. These companies need funds to grow, so it allows them to absorb more capital which makes deploying $100B a lot easier.
Now Uber has leverage because of it's network. If you open your iPhone and you don't have an Uber waiting for you then you will stop using it. So actually there is real value in the network there.
For WeWork there is no "tech" and there is no leverage. Certainly the tech side is obvious, just look at the employee head count and the leverage side is also non-existent. There being more than 10 WeWorks in the same city for me doesn't actually make my experience of WeWork any better or worse. Which has been proven by how many coworking startups have sprung up to compete with them and are having no issues filling their office space.
So here you have a large money losing business with no leverage and as a result giving it a tech multiple was blindingly obvious to many people that it was a bad idea.
With that the Vision fund is running into real hot water. They need large growing companies in order to deploy their investment capital, but investing in money losing businesses is a risky, especially when the largest money losing businesses don't have real leverage and aren't real tech companies.
This just all unraveled a bit quicker than Softbank would have liked, but it isn't at all surprising.
To see other investments of theirs falter isn't surprising either. Because they will all follow the money losing model in order to absorb the capital, but unless they truly offer leverage then they will be either displaced, or they won't provide enough value to eventually out run their costs.