In order for someone to be willing to pay you interest they have to have some kind of direction in mind that they expect will return more money than the cost of

In order for someone to be willing to pay you interest they have to have some kind of direction in mind that they expect will return more money than the cost of the interest. If they have a solid plan that is worth investing in, why not pursue it yourself and reap all of the rewards? Management of that might be unrealistic at individual scale, but when you're the size of Google you can go off in all kinds of different directions without much impact.