The thing I kept thinking of, especially whenever they were talking about "enough to be financially secure" was a quote from Ted Turner just after he donated a billion dollars to the UN. (I can't find the quote online, I saw it on TV)

It went something like this: "I've found that a person really can't spend more than $200 million dollars in their lifetime. Even if you make no attempts to save it or spend it wisely, it's very hard to squander $200 million so badly that you are left with nothing" (that was the gist, at least, but this is from memory)