Man, it really seems like amazon is just going to be everything at some point. In, say, 20 years will some meaningful percentage of all the money I spend somehow funnel through amazon? Kind of seems that way.
To be honest though, I personally wouldn't mind Amazon controlling more aspects of my life for now at least, however threatening to various liberties that might be. My overall experiences with their customer service have been stellar, which is much more than I can say for some of the other monopolistic companies I have to deal with.
They launched in Australia (the newspapers were predicting the end of retail). They have what, 30% of products available here? Then they launched Prime - except they obviously haven't hired anyone who has used Australia Post before. You can't expect a Prime 2 day delivery if you use standard Post.
All this, and they thought restricting access to the US version was a good idea.
Amazon Australia: death by 1000 paper cuts.
When eBay looks like a better option, you've really screwed up.
You can't even get Express Post items in 2 days about half the time, even tho they "Guarantee next business day delivery"
Amazon already has 5% of the total retail market in the US. I consider that a meaningful percentage.
More anecdotally, one of the discord servers I'm in recently had a trend where people shared their total yearly spend on Amazon. Upwards of $10-20k were not uncommon. (The data source is definitely biased though, as it's more of a hobby-related discord == upper middle class segment).
Source: I work for a monopoly in the EU and while my company is heavily audited and regulated to ensure we operate fairly, we are still free to run as a monopoly.