I didn't say anything about massive. On average, computer code has about one mistake per ten lines of code (very roughly, of course) So once you have over a few

I didn't say anything about massive. On average, computer code has about one mistake per ten lines of code (very roughly, of course) So once you have over a few hundred lines of code, you are practically assured of having bugs. And then you throw over $100 million at the buggy code, and the results are ... as expected.