While many investors are pegging the global markets' recent plunge to wild swings in Chinese equities and the drop in oil prices, strategist Jim Paulsen said Thursday there's a more fundamental reason.

"I think the drop had more to do with the vulnerabilities of the market," Paulsen said in a CNBC "Squawk Box" interview. "We had market that was richly overpriced and investors getting too calm and complacent."