You always need luck, yes. But Bezos wasn't just lucky. He had a real, deep insight.
https://video.twimg.com/amplify_video/1821082875531317248/vid/avc1/1080x640/dnnQZSiRsedAoxcc.mp4?tag=16
Funny, now their margins are negative for selling things like books and signifigantly positive for their web services.