I'm watching someone on YouTube renovating an old house and they use it to make out places that leak heat and need better insulation.

I had the same issue/concern and so shared the price with someone else. We intended to timeshare but they were kinda done with it after a few days whereas I love it and use it at least weekly since like three years now

The local library has one for loan. I'd recommend getting that before you buy it outright indeed

I measure everything, like

• "is everything in this microwaved meal heated through, no cold spots?" (after stirring)
• "oh it's freezing out, I'm curious how cold food got that we transported in the trunk of the car while the cabin was warm" (so I go and point it at the trunk area to get an idea of the cold/hot spots, as well as the food of course)
• new phone/laptop: I'm curious how hot it gets to the touch
• The insulation checks that people mention
• instantly see which pieces of laundry are not 100% dry yet. You can feel it individually, but the wife acceptance factor is in getting an instant answer for a whole rack
• Pouring a cold liquid into a hot one (or vice versa) is beautiful to see. Like watching a fire, except it's at 320x480 (but it's a new kind of fire! Exciting nerdery!)
• I've tried finding animals in the forest but it turns out that branches, leaves, ground, sky etc. all have very different temperatures and you can't easily make out an animal among all that. Was interesting to try though, I enjoyed myself for a few hours across different visits ("it's cold out, maybe now animals show up with better contrast? Are the plants keeping warm? Let's go see!")
• cat buttholes =). I noticed randomly at some point that this is where they leak the most heat, and figured getting a few baselines while our cat walks by is good to have ahead of the time you want to know if their temperature is elevated
• gimmick to show people who haven't seen it before. If they're interested, you get to talk about how it works and what things look interesting
• edit: wait, I remember a legit use case: we used it to find where we can drill. One of these magnetometer devices was going wild and we couldn't otherwise locate the cable that runs to an outlet. Connected a 1500W space heater for iirc 20 minutes and it was crystal clear! /edit.

Still not sure if this all justifies the price but I own it now and I'm making the fullest use of it and enjoy it :)