Your average American hasn't attended for a couple of reasons:
a) It's SUPER expensive. Not just to go, but if you notice, wherever the Superbowl is held, it's in a neutral stadium, which means fans of BOTH teams have to travel to get there. Which means planes, hotels, rental cars, etc. etc. etc. beyond the extraordinary cost of tickets themselves.
b) It's super hard to plan for. This year, the Superbowl will be held in New Orleans in 59 days, which means right now is the prime time to book plane tickets, hotels, etc. But who's going to be playing? Is it going to be "your team"? Nobody knows, because the playoffs don't even start until January 11th, and the two teams going to the bowl won't be known until January 26th, just 13 days before the Superbowl itself.
Which means fans have just 13 days to figure out how to get there to support their team, hope they can get tickets, hotels, etc. Short term travel booking like that is super expensive (see point a) and beyond the reach of average Americans.
c) It's actually a better experience at home. Unless you LIKE being in a stadium with 76,467 other fans, paying premium prices for snacks, and dealing with the traffic nightmare getting to and from the stadium, it's better to sit at home, in your jammies, in front of a 65" television, watching all the plays in slow-mo 4K detail, with color commentary telling you what to think about it.
As @jordanlund@lemmy.world says, most Americans will not have attended. To add some additional context:
Only about 1/3 of the tickets are allocated to the participating teams to distribute (generally giving premium/long-tenured/whatever season-ticket-holders a right of first refusal at the extortionate prices) Here is a breakdown that I assume is decently sourced and jibes with the conventional wisdom. Partly because of this, the crowd at the super bowl is known to be large but underwhelming and "plastic" even by American standards.
The super bowl is better on TV in large part because high level American football has been engineered to be an ideal sport for TV consumption. It's naturally a very stop-and-start game, and rule changes (some explicitly for the benefit of broadcasters) have doubled down on that. There is unfortunately a lot of down-time when you're at the stadium in person, and games take 3 to 3.5 hours on average, with some variability, versus the fairly predictable 2 for a regular league match of association football. While you will see a lot of ad breaks on a broadcast, you're not a captive audience at home like you are in the stadium. Still, in the streaming era, live sports has been a reliable and lucrative legacy revenue flow that only may now be cresting.
For the Super Bowl in particular, this means that for decades the game has been the showpiece for the advertising industry to launch new campaigns, try to make lavish and meme-worthy ads, and just generally flex. Famous super bowl ads live in the American consciousness for a very long time, and it remains a bastion of the eroding monoculture. It's also even longer than most games.
Speaking of which, the halftime performances (and to a lesser extent the de rigeur national anthem performance) are also cultural touchstones, and are generally better experienced at home.
Because of all that, the "super bowl party" is the most iconic way Americans experience the game, so it becomes a social event, but not a die-hard sporting event, except for fans of the teams involved, or if the play lives up to the standard the NFL and media hopes for (not guaranteed due to the rhythms of american football and the NFL league calendar).
I think it's similar to the Time Square New Years Celebrations. Everybody knows about it and has probably watched it. But only super dedicated people will actually go in person, but I bet it's quite the experience
It's a lot easier to do something at home or locally with people you care about and a lot cheaper too
I went to Time Square on New Years once. It was awful!
People start lining up for it the morning before, and there’s limited space in the actual area around the ball. I lined up at like 3PM and got a spot without being able to actually directly see the ball. I could see some of the fireworks, and they had big TV screens set up but tbh what’s the point of that? To actually see the ball you really have to be waiting in line well before noon, so maybe like 16 hours or more of waiting?
Also while you are waiting, you are checked before you come in so you are limited on what you can bring to entertain yourself. No alcohol. They won’t sell food or drinks so you have to bring that yourself. If you leave to go to the bathroom you risk losing your spot. There’s no trash cans anywhere so people just throw trash on the ground.
So all those people you’ve seen on TV? They are starving, bored out of their minds, and have been sitting outside all day long for the like 5 minutes of spectacle. Absolutely a wonder how they manage to look cheerful for the cameras.