Example: how is it possible that Google couldn't make its own successful video streaming service and had to buy YT for billions? They had the expertise and money, but it didn't catch on.
Why did previous tablets fail and iPad succeed? Microsoft was into tablets long before iPad.
Sometimes, no matter how rich or smart you are, or how good your idea is, it's going to flop because it didn't encounter the perfect environment and moment to take roots. Because not even rich players can control the environment, they resort to buying promising startups trying to hitch a ride to success on their wings, or alternatively, the YCombinator model of seeding and grooming startups. How many of YC startups flopped, even with help?
Edit: seems I am not in agreement with the crowd. Instead of downvoting, please argue in replies.