This is not true because If the temple teaches their followers to donate everything until they become penniless, the temple should have only poor, indigent followers. How can the temple have only wealthy followers?
The reality is, the temple teaches people to be economical, diligent, and never associate themselves with all vices. Instead, it teaches people to make donations, follow the precepts, and meditate. When merits bear fruits, their financial status improves, so they contribute part of their wealth in donation because they faithfully see the value of supporting Buddhist activities.