Hey, you do you. You are certainly entitled to drive as calmly as you want.
But the rest of us are still going to drive 70-80 mph, because we can, and we want to. So keep in mind that your slow poking, if it is making other slow-ish drivers or semi trucks have to pass you, is creating real danger back behind you. Whenever a semi truck has to use the left lane to pass someone during high volume traffic times, it creates an accordian wave of slow-down braking for all the rest of us in the left lane. I've seen this cause panic stops and accidents numerous times. Not to mention all the wasted fuel for everyone having to slow down, then reaccelerate to normal speed.
All because some dude is determined to drive slowly for their own personal benefit. You might be saving your own fuel, but you're costing everyone else more and it's a net loss for the economy and environment. I'm not calling you selfish, but it's most certainly safer for all the rest of us if you go with the flow and match the normal speeds of the road. Again, this concept is in the context of rush-hour, congested commuting. Off hours, no issue.