I was thinking more in terms of investments related to the company's business (e.g.: Apple pre-paying billions of dollars to lock up massive amounts of flash storage or to fund new factories for suppliers) that often have a much higher ROI than any investment you or I might reasonably make in any investment available to us.
Large companies carrying trading/gambling departments not related to the rest of their business is, as you say, probably not a good thing.
Sure, if the money is being spent on things like stock and operating expenses that are a normal part of the business, I have no problem with that. If it's being done on an industrial scale and there are economies that go with that, it makes perfect sense. I'm just not convinced that (for example) certain large tech companies -- particularly those that are in the software or services businesses rather than in manufacturing -- need reserves on the scale they are holding for the kinds of purposes we're talking about here, which leads me to ask why the rest isn't being paid out in dividends to shareholders.
Large companies carrying trading/gambling departments not related to the rest of their business is, as you say, probably not a good thing.