One of the key traits of technology is increasing efficiency; doing more with less effectively multiplies resources. We'd have started running out of oil earlier if technological advances hadn't made cars a little more efficient than they used to be (but no more than they had to be to maximize profits). Developing new materials that perform better than traditional materials like iron stretch out the supply of those old resources for use where they're essential. Making all electrical devices use energy more efficiently effectively creates more energy by freeing it up for other uses.

About forty years ago there were forecasts that the world would run out of food and there'd be widespread starvation. It didn't happen because technology was applied to food production to produce more of it, though we're still treading water at a furious rate to keep ahead of population growth. Nowadays some Rightwingers point to the absence of famine to claim that the forecasts were just alarmism, as they argue that global warming is equally alarmist, but that's silly--the fact that a problem is avoided doesn't mean that the problem wasn't there in the first place.

You're not wrong that overpopulation is the root of many evils. But I think that you're overstating the problem by not looking at solutions that mitigate it. The real challenge is for technology to keep up with population growth; if the tech curve falls behind the pop curve, then we'll be in real trouble.