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> at it's core (pun intented) Dark matter is something to make equations fit without any other thought behind it or whether there might be several things behind it or god forbid that we juddge the equations themselves

Another way to interpret dark matter is that we can observe something using several different ways, but all those ways use gravity. When trying to observe this something using electromagnetism, we see nothing. It doesn't seem so crazy then to hypothesize that this something only interacts with gravity, and not electromagnetism.

> I mean we got relativity because of a minor discord with newtonian Laws. (the orbit of Mercury).

I don't think that's true. One of Einstein's test for General Relativity, using Mercury's orbit, came around 10 years later after special relativity was proposed, which is understood to be motivated by both Maxwell's equations and experimental results suggesting that the speed of light (electromagnetic waves) not depending on the frame of reference. General relativity (explaining gravity) seem to have been motivated by Newton's gravity not playing well with Special relativity (with mass being relative and all).

I understand the frustration with Dark Matter, but my understanding is that Dark Matter is a guess that is known to be incomplete. Scientists are shooting everywhere to try to explain the discrepancy in gravitational effects and some form of undetected matter is currently the best hypothesis (but not the only one). You say that "we accept 90% observation disaccordance", but the source of its effect is being searched for.

See:

- https://hsm.stackexchange.com/questions/622/what-was-einstei...

- https://en.wikipedia.org/wiki/History_of_gravitational_theor...

- https://en.wikipedia.org/wiki/Tests_of_general_relativity

Edit: formatting, updated links

The "it looks like there's stuff we didn't previously know about here" class of guesses has historically been fruitful, yielding, among other things, the discovery of several planets. Maybe dark matter isn't the answer, but it's not "no guess at all."

> just one Dark Something than 3 different somethings to explain anything

There are many candidates and I think nobody discarded it's a mix, it looks like a plausible scenario. I made a quick look in Wikipedia, but I didn't find anything relevant to a mix of Dark Mater.

There is(was?) some big discussion about cold vs hot (and warm?) dark mater. IIUC "cold" dark mater won. I'm not sure if there is enough details to make a good guess of the split, or if it's a 100.00% vs 0.00% case.

No, it's not quite "no guess at all". Using gravitational lensing to estimate how much mass there is in a part of a galaxy is pretty smart. It turns out that there sometimes indeed is mass (because the lensing is there) even though it doesn't seem to give off much light.

(But I don't really believe in dark matter, either. It's mostly epicycles and phlogiston.)