How high can a drone legally and practically fly?

I’m curious about the legal and practical height limits for drones. Can they go as high as mountains or higher? How do regulations impact this?

Legally, most countries cap drones at 400 feet (about 120 meters) to avoid interfering with manned aircraft. However, drones like the DJI Mini 3 Pro can reach up to 500 meters if you’re in a country with looser restrictions like Canada.

Technically, drones can go much higher, but air density and battery life become limiting factors. A DJI Phantom 2 once hit 11,000 feet, but that was reckless and drained almost the entire battery.