I don't think a gold standard is a viable pyramid scheme for a multiplanetary species. There's too much of it in space. You need something that is rare even after traveling for hundreds of years. A lot of wars were simply fought over resources. It's even better if your society uses the resource as money. The only thing I can imagine is using habitable planets as currency, this would require your galactic empire to have a dozen planets though because a single planet does not make a currency and the debt trap of borrowing 1 planet at 3% interest would fall apart because colonizing the next planet may take too long to pay off the interest. I.e. you need some planets to lose before you take that loan.

Edit: Great filter hypothesis to explain Fermis paradox. The pyramid scheme needed to enslave the galaxy is also powerful enough to destroy a planet before it develops space faring technology.