French to English Bus/Financial Finance (general) Financial crisis

A slightly unusual one, this. I'm translating a report on the impact of the current financial crisis on a major French bank. The author contends that one of the reasons for the crisis is that banks have relentlessly pursued short-term profit, and have believed that profits would just keep on growing forever. The image that is repeatedly used is "les arbres montent au ciel". I suppose it's quite a good image, as it conveys the idea of believing that trees will keep on growing forever, whereas in reality they will get to a point where they outgrow their roots and come crashing down. However, in English, talking about "trees that keep on growing forever", even though the image will probably be understood, doesn't really work - it just sounds odd.

So I've been scratching my head trying to find another suitable image. The best I've come up with so far is the goose that lays golden eggs, and the belief that it will just keep on laying them – but I'm sure you'll agree that this isn't quite as apt.

Here are some examples of the expression in context:

- "***Les arbres montent toujours plus haut au ciel***, on ne s'en rend pas compte et un jour, quand on est confronté à la difficulté, les fonds propres sont moins florissants..."

- "...nous avions un petit avantage : nous n'avions pas d'intérêts, nous n'avions pas l'illusion, nous ne nagions pas dans l'espoir que ***les arbres monteraient au ciel***."

"Jusqu'où ***les arbres peuvent-ils monter au ciel*** ?"

"Le deuxième niveau de déni était de ne pas accepter de rompre avec l'idée selon laquelle ***les arbres montent au ciel***."

Feeling inspired and creative? A vos marques !

Thanks in advance for your ideas.