This.
The outcome of the game on paper is 50/50, assuming that they are going to decide it by a coin toss. They aren't. If you do research, and choose the 4 games that week that are most likely to cover the spread, your odds are way higher than 50/50.
Yes, this is still a feat and it could well be a scam to advertise the site. But it isn't a 1 in 2 septillion feat. If you can cherry pick games to make it a 60/40 proposition instead of 50/50, the odds are 2.4157877732485223e+15 which (if I'm doing the math correctly) is about 2.4 quadrillion (or 2,415,787,773,248,522.3 more precisely). That knocks 9 zeros off your number.
Take it a step further and only pick clear favourites, and never get an upset. Up it to 70/30 and your odds are about 1 in 63 trillion (or 63,529,072,894,891.32 more precisely).
Take it a step further, manage 80/20 odds and your odds are 1 in 141 million (or 141,347,765.18227139)
How long would it take for 140 million bets to be made on 81 games in a single NFL season? My guess: not long at all. The difference is that in this day and age you'll hear about it when it happens that someone gets it right. Especially if it's good advertising and the company behinds it pushes the info out in a press release that gets picked up.