While you're not necessarily wrong, "ego" gives off a pretty negative vibe. I would say it's quite often personal dissatisfaction of the status quo.

I support what they are doing. Wheels sometimes get better when they are reinvented.

I'm not one to declare other people's motivation, but it strikes me as very odd that there isn't a "So, here's what's irreparably wrong with dpkg/apt and rpm/yum".

it's fixing a (real or perceived) problem with nix, not with dpkg or rpm.

Well, there isn't a "So, here's what's wrong with nix" either.

there kind of is, if you read between the lines - their usp is the scheme interface, which provides a "proper" programming language with which to interact with the packaging system. they don't explicitly call that out as something wrong with nix, but it's clearly what they feel they do better.

What relation would you say ego has to scratching one's own itch?

I think the concepts are intertwined, if you are going to scratch your own itch and then release it for the rest of the world to scratch theirs.

"We will encourage you to develop the three great virtues of a programmer: laziness, impatience, and hubris." — Larry Wall