But that highlights the inconsistent usage of the term. Often it's used to just mean "a company with a lot of engineers with similar practices and culture"

How much profit does Amazon show?

Amazon made $2.62 billion in the last quarter, and $3.5 billion the quarter before that.

Amazon makes a ton of money, and (quite transparently I might add) they plow a lot of their earnings from some of their businesses into investing into their other businesses, which is what most investors want.

This is completely different from Uber and Lyft, where it's not clear that their profit potential supports their current valuations.

Amazon has demonstrated its ability to show a profit. Uber and Lyft have not.

If the acronym is only about profit then it is both misused and excludes other obvious companies like Microsoft.

It’s not entirely about profit, but I would argue you have to show a profit, or, demonstrate you could show a profit like Amazon has, to be considered a “top company” in any sense.

How does it exclude Microsoft, who reported $8.4 billion net income for Q2 2019?