Elon Musk ventures = solves real world problems while maximizing fun.
It's interesting how you paint Amazon and Walmart. Let me bring up just one example:
The short term price squeezing means manufactures are responding by providing lower quality items to Amazon, just like what they do at Walmart. (Try buying a box of name brand Pampers diapers on Amazon right now and compare them with the same SKU at, say, Target) And all the more power to them if that's their goal. But long-term it isn't a sustainable strategy, business or environmental.
Low-quality products equals more landfill and less money in consumer's pockets overall. It also means a very small market for product re-use, such as buying second hand. I grew up with 20 year old appliances from a local thrift shop. Every appliance I buy now seems to have a 24 month shelf-life, with the liability of having to dispose of unrecyclable materials. I'm telling you, net negative.
Nice anecdote, maybe you're just abusive? I buy simple appliances from Walmart and they last fine. I have a $15 drip coffee maker that has probably made about 2000 pots of coffee now from them and it still works. I'm telling you, net positive.
It's a lot harder to argue that another player in the market could have filed the niche that Elon identified and continues to expand.
SpaceX is a government contractor -- an amazing one no doubt, but without the custom of the government they wouldn't exist. Tesla grew up on government subsidies for years and when faced with real competition, Elon suggested it was time to stop the subsidies. He may be doing good for the planet, but he is an ego driven hype machine.