You can’t trust thermostat ratings

I bought a 185 thermostat, it was stamped 185, yet my engine consistently runs at 170, no matter the season. Verified with a laser thermometer.

Is it worth the time and energy to swap it out?
You can use less fan, or a higher rating stat...but... idk. It's your car. Idt it would hurt it. There is an expansion rate at a given temp for cast iron and I guess you would want to maintain a range in regards to the clearances vs temp spikes @wot ...its really overthinking it though. Lol