Well whether frugality and restraint are strengths or weaknesses is a completely different topic, and a matter of some sociological debate where it's not clear what's "good" and what's not.

When you think of societies that live frugally and with restraint, who do you think of? Usually - certain primitive societies. Like the native Americans, often they were forcefully conquered by more aggressive, less frugal societies with advanced technology - technology that was developed because of their un-frugal nature.

But let's ignore man-made war for a second - imagine there's a giant meteor headed towards earth. Which version of earth is more likely to survive - the current one that spent lavishy on figuring out "what's out there" with the space program and weapons, or a version of earth where everyone lived frugally, with restraint, and in complete harmony with nature, only using renewable resources? I don't think the 2nd one - they'd never even figure out what was beyond the blue or black sky.

I do actually agree often about "conspicuous consumption", but there are more solid and practical reasons why society promotes more excess than having just the "what I need to get by" level of stuff.