It is not easy function well in a society of other apes when your IQ is 3 standard deviations from the average.
You have to constantly dumb it down, for your parents, your teachers, your bosses, your friends.
In school, most teachers will hate you and be constantly afraid that you are going to embarrass them in front of the class or other teachers.
At work, your not so bright bosses will be afraid of you thinking you are after their job. So what do you do? You play it dumb so they
feel superior.
Hard to find other high IQ friends, unless you go with the flow and play it cool and dumb jock.
High IQ individuals have harder time finding suitable mates, and when they do find them, they have 1-2 children at most.
Opposite is true for people with lower IQs, they are more social, they mate more frequently, have lots of children, before and after they get married.
Try to score with a cheerleader (or any female for that matter) when you are branded a geek. Most people are afraid of smart people.
They don't know what to say to them, they are afraid that they might say something stupid.
Being smart is not considered a desirable quality in our societies. Being funny, dumb and cool is.
Information age plays some role too as people stopped memorizing information. How can you make any inferences if you don't remember anything?
Diet might play some very minimal role, IMHO.
I hear these complaints often. Being smart has no drawbacks whatsoever.
Girls love smart guys, other people do as well. No one feels threatened when you are nice to them and when you show them that you understand them.
They would love to listen to your smart advice if you show them that you are on their side and that you won't judge them.
It isn't rare to see smart people blaming all their social problems on being smart and it is very obvious that it is just an easy excuse that doesn't make you feel bad about your imperfections. Being funny is something smart people are really good at, not dumb people.
It isn't hard to find very popular smart people. Most popular adults are quite smart, this tends to be very important quality to everyone in adulthood.
As for technology allowing people not to memorize a bunch of small unconnected details, that doesn't have anything to do with intelligence.
If you want to use your intelligence and deeply understand a certain subject, quick searches on the Internet will not help you at all.
You need to spend time if you want to understand something. If anything, technology made people who can memorize a lot of useless things obsolete.
Now everyone can tell you what is a capital of some small African country in a second, but very few will be able to explain to you some deep concepts in physics, math, chemistry, etc. This is a good thing. Chimps are a lot better at memorizing things than humans anyway, this is not a sign of intelligence. This is a good tool for intelligent people that allows them not to worry about exact data, but understand the concept instead.
As for the number of children thing, that is very debatable and not really good to generalize.
There are societies that put a lot of importance in education, intelligence and having a lot of children.
Not just individuals, but whole societies.
That stereotype usually comes from the relatively recent increase of population in developing societies (and societies that are now developed but experienced this increase when they rapidly developed in the relatively recent past). As societies develop, medical services in those societies develop as well. And a lot of people forget that child mortality was very very high before antibiotics and vaccines. When these advancements in medicine (and hygiene) arrived instead of 80% of your children not reaching adulthood people started seeing these numbers drop to virtually 0%.
That is why it made sense (and in some very poor places still does) to have a lot of children, since most of them died.
They sometimes weren't even given names until a certain age. This took time of course for people to naturally adapt to and therefor there was a large boom in population that exist in developing countries now.
This made a stereotype that poor people have more children (which was true in the past when most of them died) but now some are in a process of adapting (having a lot of children with low mortality) or are still experiencing these horrible rates (some very poor African countries).
Nowadays it doesn't make sense to have more than 2 children, because competition is higher and it is harder to raise more children with enough education, skill and wisdom to get a job, family and prosper and earn rank in a world where there are many educated people. Poorer people didn't always had a chance to compete on such level and had to insure survival first and competitiveness later by having more children that they couldn't educate, but had to have in order for few to survive.