It's less about risk aversion than it is about position, size, and complexity. As these things grow, the incentives change and the ability to understand what the organization even is becomes impossible.
A startup starts at the bottom. It begs investors, customers, and employees from a position of optimism and humility. The organization enthusiastically changes itself to find a good balance between those three or it dies. As the organization grows, it starts demanding everyone else change for them instead. Google's interviews are an example. Its famous customer service is an example.
Then we get to size and complexity. Thanks to Dunbar's numbers, we know that there are numerical limits to a human's ability to know people. This makes sense. I can know everything about 6 people, most things about 50, and keep track of about 250 well enough. As the organization grows, your ability to know it disappears. You begin making abstractions. Instead of knowing exactly what Susan does, you say she works in X Department, for Y Initiative, doing Z position.
Google is so big that one person can't understand it anymore. The inevitable reduction to a corporate abstraction occurs and then people treat it like the X Company, which is just like Y Company but makes X instead of Y. Short term revenue and expenses are the only measures at the end.
And in this faceless abstraction, the professional parasite class infests and extracts resources and morale. Eventually the C-suite stops fighting it and joins in on it until only the sheer size and momentum of the company keeps it going. Maybe an investor group will come and force a rework of the company, but not before the company is just a shadow of the shadow of its former self.