My layman understanding is that investors think Amazon still has enormous room to grow because Amazon's current market share of the entire US retail industry (o

My layman understanding is that investors think Amazon still has enormous room to grow because Amazon's current market share of the entire US retail industry (online + offline retail) is about 7%. The one thing that will make online shopping appealing to far more consumers is same-day and eventually 1-hr deliveries, irrespective of your location in the continental US and the only way to do this reliably is when fulfilment is automated end-to-end. For fulfilment to be fully automated, self-driving cars and trucks need to be a reality as that is the only way to cap shipping costs in order to guarantee Amazon's promise of low prices. In order words, investors think Amazon's market share will grow even more as distribution costs start to fall when the shift from human to self-driving trucks becomes economically and technologically feasible. Self-driving cars are still at least decade out, IMHO. Add another decade for regulations (e.g. which party is directly liable in X types of accidents?) and infrastructure (e.g. cooperative signalling, standardized charging stations etc) to catch up. This is why Jeff Bezos likes to stress that it is still Day 1 at Amazon.