I don't think they hate Nintendo, Nintendo software is just too expensive for them

I think it's more that once they get to high school they want to A. Play GTA and call of duty with their friends and B. The peer pressure etc to be "cool" and play violent 18+ games and not Super Mario.

People grow out of that mindset after high school.

Nintendo cleans up with 18-30 year olds in particular.

Once people get out of high school and have their own disposable income, they come running for the Switch.

Kids are honestly a little weak across the board, even 9/10/11/12 year olds being below 30-somethings and even early 40s folk is a bit of an eye raiser.

21 now being the leading age demo for Nintendo is interesting because I remember ages ago Phil Harrison who was with Sony when they launched Playstation said 20-21 was the exact target age they aimed the Playstation for.

Something this shows is there are still not that many people above the age of 50 into video games but by the 2040's all age brackets except 70+ will have grown up with them so that'll change before much longer. Also kids are now pretty likely to grow up having at least one parent into video games which will help foster connections.

so the idea I get from people I know is not wrong at all :P

one more reason to drop things like friend codes and pointless chat sensoring as they really hurt some game potential - I coudln't even post the word 'stupid' and to think it was directed to my damn self

Doing stuff the parents do is soooo uncool, so kids in the future will read a book while their parents want to play Mario Kart with them.

Pokemon effect. Kids it's cool to play Pokemon. High school not cool. College it's cool again!

The Switch is for the tender ages of the 20's and the ripe audience that is the 40's. I'm sure there are a certain percentage where these forty year olds are the parents logged in on Switch while their teens are playing it.

I don't know if we have different cultural backgrounds, but I can't recall this particular behaviour in teenagers. I think teenagers are mostly playing multiplat free games such as Valorant, League of Legends and Fortnite. I see none of those games as particularly violent, they are competitive and gregarious games to play with friends that can be found in any platform and even basic PCs can run just fine. Switch (or any console for that matter) has a higher price tag, so for a teenager with no income the only way to get one is to get one from your parents, it's not far fetched that families where the parents already had a console will be played in the parents accounts instead of their children. 

Once teenagers start working and/or having their own income the demographics start to rise as well with big spikes in the ages of 18 to 22. I don't see why teenagers who hate Nintendo suddenly start loving it again just 2 years later

From the very first trailer it was clear the Switch was gunning for the 18-40 market first and foremost and given its meteoric success it comes as no surprise that they've successfully courted their target demographic.