or even better use something like putty to hold your three mirrors together temporarily while you fine-tune the angle and then glue them solid

Also from the perspective of engineering, if I wanted to DIY an accurate corner reflector cheap then I'd use the property of returning laser beams to their origin over distance to do it. Make a jig to hold the three mirrors, make sure they can be fixed to the jig firmly and glue them up. Test the ability to return a laser over distance. Calculate (somehow...?) the error in the jig, adjust it, rinse and repeat.

Another idea for a far cheaper way to turn the tables: create some fine mist or dust in the air near the dot so that you can see the beam then take a picture, or even better a video where you move around a bit to create proper perspective. Then you or authorities should be able to better identify where the beam originated.

That's the mirage of value. It's a mirage 'cause:

a) it isn't creating that value but taking it from somewhere else (past IME contestants and test preparers, StackOverflow, the job market, etc)

b) users fight to bid up the value of a single set of fixed capabilities, like rats fighting over the same scrap of leftovers. The market floods with generic copies of whatever stuff it can do.

That is to say it's utterly, humorlessly laughable to think that we're trending towards these things doing a whole economy worth of work.

Yes. Every single stock in the S&P500 took a dive that day