The attitude of Eldar towards the Imperium

Question

Why are do the Eldar feel so superior towards the Imperium? In various instances we are shown and told that a Space Marine is way stronger (raw strength) and close to the dexterity of an Eldar warrior. It would be understandable if they would say that about the Orkz / Tau but the Imperium has shown time and again that they are not only powerful but also smart.

So all in all, why are the elliptical-heads so smug?

LE: I do not care about real-life comparisons, they are not what I'm looking for here. I'm asking how a 60+ million years race can consider itself superior over a 70 thousand years species considering the fact that they kind of eat dirt every time they show up. Is there a reason for their superiority complex (expect for making up for giving birth to Slaanesh (easily corrupted xeno-scum)) like making contact with the Imperium / humans in general and someone shot himself in the foot or something to prove that humanity is stupid enough to be called Mon-Keigh?

All books, codexes, drunk jokes by GW or any other "official" sources are welcome. (take the language with a bit of fun, no hate around Sol Sector please)

Answer 1

It's worth pointing out that Space Marines​ are a bad example. They're a fraction of a fraction of a percent of mankind (dont let the number of models sold fool you!), and in no way representative of the Imperium as a whole.

The main thing, though, is that human actually are inferior to Eldar in the ways from Eldar care about.

Consider:. Eldar are far longer lived than men, effectively immortal if you account for the Boneways. They are in tune with their emotions and psychic potential in ways that is far more fundamental than even the best human psykers can manage. Third, they actually understand and build their own technology, where most humans treat tech with near religious reverence and cargo cult mentality.

Lastly, realize that there are plenty of humans who think themselves superior to other groups of humans, and they have even less real differences to point to than Eldar do. Arrogance doesn't have to be based in objective reality. :)

Answer 2

Let me explain this with a parabole: Imagine, that our current XXI century human civilization collapses and only handful of humans survive. Then suddenly, in matter of few years rises primitive civilization of rats that knows how to use basic stone tools and they believe that world belongs to them. Wouldn't you feel superior to those creatures?

Eldars civilization lasted about 60 million years, during that time they controlled most of the galaxy. In comparison, the Empire of Mankind is only 10 thousand years old and barely 60-70 thousand years ago sharpened stick was the pinnacle of our technology. Just for that reason Eldars think that they are better than us - crude, ugly, primitive upstart race^*

Eldars as a specie are also superior - they live longer (or even forever if you count the afterlife in the wraithbone), they are smarter, able MUCH, much better to resist the taint of Chaos - and that's while they are much more attuned to warp - Even Emperor, while much more powerful in the raw power was not able to read the future like typical Farseer.

Yes, they can see that Space Marine is stronger than Eldar Warrior, but so is a bulldozer or an ape - do you think that dumb tool is better than you, only because can lift heavier things?

Finally there is simple pride - Eldars believe that they are simply better than everyone else, something that is especially visible among Dark Eldars, who treat even their own as either "tools that I can use" or "fools that let me follow them them until I'll be strong enough to take their place".

^{* Surprisingly they have more respect for even younger Tau, but there are hints here and there that Eldars were actually involved in creating Etherals and pushing Tau onto path to stars}