Tire pressure question

So I recently got my first gravel bike, Specialized Crux 4 DSW, after riding roads exclusively for the past 10 years. I had never really looked into tire pressure and rolling resistance before but this seems to be a big deal now.

My question is why does the PSI seem so low when using the Wolf Tooth online calculator. I weigh approx 192lbs and the bike is about 21-24 pounds with gear. Running 700x45 Pathfinders from Specialized, and it’s hot hot here in Louisiana. Road are trash and gravel will be very mild entry level stuff.

The calculation is setting me around 40psi which I’ve never ridden on but man that seems so low. What am I missing with this trend or suggestion? I’m sure I’m just very naive.