is the fact that it's dropping below $30 right now mean that the previous $100+ prices were completely inflated compared to COGS? The massive fluctuations for something that you just need to pump out of the ground doesn't make too much sense to me (compared to, say, price of potatoes)
1. strategic decisions to keep the price low (in some cases below the cost of production) to make it uneconomic for competitors to invest in oil projects
2. time lags in the system. e.g. the global economy went into recession the last time the oil price spiked. that'd reduce oil demand in some cases. now as prices are much lower again we might expect demand to keep growing until supply isn't able to satisfy demand (again), then the price will spike again
3. (long term trend) oil is becoming genuinely more costly (in physical terms - i.e. required energy) to extract as we deplete the low hanging fruit. i guess this makes it much harder / impossible for supply to ramp up and satisfy demand in a short enough time period before another recession is triggered. this isn't necessarily a problem in itself but perhaps it influences the behaviour in item 2
This is probably only semi-coherent. I read the "limits to growth" book a couple of weeks ago, and one of the claims there (from a system dynamics perspective) was roughly that any system that combines both delays in feedback and erodible limits is expected to either behave like "overshoot and oscillation" or "overshoot and collapse".