Microsoft founder Bill Gates on Monday said Amazon’s plan to have drones deliver some products in four to five years is an “overoptimistic” timeline.

But the tech billionaire said unmanned vehicles in general will have more of an impact on society than people realize — “in positive ways.”

“Something like books you can get literally at the speed of light, but physical products delivered by drone, I would say he is probably on the optimistic or perhaps the overoptimistic end of that,” Gates said on CNN. 

Amazon’s CEO Jeff Bezos told “60 Minutes” on Sunday his company is developing drones that would deliver smaller products purchased online. 

Bezos said the technology is still years away, but when pressed, he said it could be possible in four to five years. 

A Federal Aviation Administration ruling on how commercial drones would impact the airline industry is scheduled for release in 2015. 

And some senators, including Ed Markey (D-Mass.), have called for increased privacy protections before expanding the use of commercial drones. 

Gates, nonetheless, said the technology could be used for other purposes beyond Amazon delivery — including low-cost shipments of health supplies to hard to reach places. 

“It is great that people have dreams like that,” Gates said. “If we can make the cost of delivery easier, then it's not just books, it is getting health supplies out to tough places.” 

He added, “Drones overall will be more impactful than I think people recognize, in positive ways to help society.”