Over 45 million folks in the US placed NFL bets in 2021! The crazy thing is it's only going to increase in popularity as more states legalize sports betting. Because of this high amount of liquidity, sportsbooks rarely hang a bad point spread in the NFL.
No, you can't base a bet solely on whether or not it's a perceived sharp side or a perceived square side. While fading the public was a proven money-maker a couple of decades ago, the average gambler now has access to all kinds of relevant information. Public sides sometimes win and sharp sides sometimes lose.