Apple faces a few challenges with their piles of money, in no particular order:
* The sheer scale of the money pile. You can't effectively fund a low-risk $100B project. They're still expanding about as fast as is logistically reasonable while keeping talent top-tier.
* The scale of Apple production. This one is pretty limiting - a lot of cutting edge technology simply can't be produced at the scale that Apple products sell at. They typically don't fund projects that they won't be able to launch at full scale. There's some speculation that they'll start to pull away from this by doubling high-end iPhone price to depress demand for it, allowing them to sell higher-end, lower-yield technologies.
* Their history with near-bankruptcy. They'll likely never have another product as successful as the iPhone. Cash hedges against business downturns.
* The sheer scale of the money pile. You can't effectively fund a low-risk $100B project. They're still expanding about as fast as is logistically reasonable while keeping talent top-tier.
* The scale of Apple production. This one is pretty limiting - a lot of cutting edge technology simply can't be produced at the scale that Apple products sell at. They typically don't fund projects that they won't be able to launch at full scale. There's some speculation that they'll start to pull away from this by doubling high-end iPhone price to depress demand for it, allowing them to sell higher-end, lower-yield technologies.
* Their history with near-bankruptcy. They'll likely never have another product as successful as the iPhone. Cash hedges against business downturns.