I'm afraid it is the real world and it is a reflection on your aptitude towards certain jobs. That's not to say it is the case for everyone, nor is it to say intelligence is important in all positions or situations (it's far from the most important thing IMO).
However the fact of the matter is that IQ is a very good indicator of ability
WHEN put in context with other assessments. It is not great on its own (before someone points out the geniuses who are out there that can't tie their own shoes), but it is a viable part of a collection of assessments (and one used a lot for that purpose). Cognitive complexity has been researched in depth if you're interested in learning more, I certainly am not!
Oh dear, life isn't fair. Move on? I hate to sound harsh, but you're still in the education mindset where everyone should have an equal opportunity. That's not how the world works. Whatever the reason for you not going to a top 10 university (and again I stress, I'm not in one of those either), that is your own problem. From the employers prospective they can view top universities as a filter on applications. While that filter may not be perfect (there will be good candidates denied an opportunity) it may make very good business sense due to the costs of interviewing 1000s of applicants.
At no point have I said people should be given a job because they are rich.. That is not the scenario the OP presented in the fourth option. They said if the position involves persuading rich people to invest (a viable job), then is it OK to only look at certain universities. This doesn't involve the candidate being rich, it involves them having gone to a posh university like Oxford (which you do not have to be rich to attend). That does present a certain image and I see no issue with employers capitalising on that.