why did the west commit to multiculturalism?

[Ironside]

There is no country in north and west Europe with a 90% European population, with, I think, the exception of Ireland and Finland. There's none in the America's either, save perhaps for Uruguay.

Depends on what you mean by European. Most immigrants are still European after all. But if you narrow Europe a bit so that for example former Jugoslavia ends up as not European, then you're correct. So there's less than 90% of a western European population yes. (Swedish data is 14% foreign born, of those are 60% European. The group born with 2 immigrant parents makes this larger, but I'm not finding the data for that one. It exists but isn't at the same location).

I asked for a source.

Your easy math does not hold up, I am afraid, as it is so easy to flick the argument around.

See, why should we accept a disease ridden Somali analphabet, who is too old to school properly and will put a burden on our healthcare. Nevermind then opening up for his entire village to come?

Do not get me wrong, I think some immigration does a nation good. However, from where I am, immigration is costing us, not helping us. So again, source?

I refuse to see immigrants as some "lottery win" out to do us any good when it comes to economics. I refuse to see it because everything I have seen and heard of point at the very opposite.

Or are you people in Norway being angry at us Swedes for hogging all the immigrants to ourselves?

Does the people in Europe at large have a ill will towards Sweden for grabbing all the "future gold"?

Not even the socialist party in Sweden (socialists, remember? The ones you are a huge fan of) make any claim that immigration is good for the economy, as they have been proven hugely wrong. Instead they urge to the soft side of the debate, IE, "Think Of The Children".

Immigrants are quite a mixed group, but those who stays are integrating with time (=becomes more statiscally simular to the rest of the population). So atleast their children are a net benefit.

Personally, I've never lived in a ghetto, even if I've been living in above average immigration areas.
I've had Iranian, Iraqian, Indian, Chinese and Chilean classmates (not at the same time, so they haven't been many) and not had any problems with them.
I've also worked a bit and talked to the more failed ones. Older Burmanese refugees that's been living here for years still without knowing any Swedish (the ones I worked with were training a bit with theirs though). But on the whole I've encountered fairly successful integration cases. So for me it's not a problem to encounter some more with the same story.

Those areas where it has developed into a ghetto is of course a problem so I can get why you are more critical, even if the Somali bringing his entire village is a huge statistical ourlier, should he even exist (the ones bringing the entire family should exist, but being rare).

Immigration is what's keeping the population growing in Sweden though.