A couple things at play here I think. First, this isn't a very sexy matchup. Neither of these teams were expected to be here at the beginning of the season and neither has an elite Quarterback (although Drake Maye from the Patriots might be developing into one). There is a lack of star power aside from a couple guys. They are just really good, complete teams that play well in all facets of the game.

Seattle fans don't travel well. They come out to their home stadium but they don't go out on the road to support their team. Patriots have won 6 Super Bowls in the last 25 years so while the team hasn't been good for a few years and the fanbase is excited about this young team they don't have the same desperation to see their team win or connection to a dynasty like the previous championship team.

And finally Santa Clara isn't a great place to host a Super Bowl. You can stay nearby but there isn't much else to do or you can stay in SF but are an hour drive away from the stadium. SF is a really expensive city as well so hotels are probably quite pricey.