In the past, raw materials were the majority of the economy, and this meant they were worth fighting over. Nowadays raw materials worth very little compared to things like having good infrastructure, an educated workforce, etc.
Yes, education and infrastructure determine the heights an economy can reach, but without raw materials you have no economy. That's why it's worth fighting over.
Modern warfare is hugely expensive, and it will result in huge damage to that country's infrastructure and workforce. So you'll wind up crippling 95% of their economy in order to steal a small proportion of the remaining 5%. It's unlikely you'll even break even.
It's far more profitable to trade. No infrastructure is destroyed, and you get a feedback loop of wealth creation.