Consider that the oil and natural gas industry is a capital-intensive industry drawing upon little labour or, for that matter, not necessarily having much of a connection at all with thye wider economy. The ambitious corporations or states which happen to control the industry have massive financial resources at their disposal, regardless of what happens to the wider economy. This can encourage very bad policy-making--the Ba'athist militarization of Iraq comes most quickly to mind.
In a science-fiction context where alien artifacts are presumably either rare or difficult to exploit, control and use of these artifacts would be limited to a select few. It would be difficult to insert these artifacts into the wider economy, at least until reverse-engineering proved profitable, but these artifacts would still influence the wider economy. The artifacts would exist apart, exerting influence but not being influenced in turn, providing their owners with a vital edge over non-owners.
Yes, I've been watching Babylon 5 lately. Why do you ask?