Dragon's Lair was a big earner too, it used some different technology in the form of a laser disc player which made for stunning graphics at the time. What made it especially good at earning was it cost money to continue playing even if you didn't die.

I did some looking into DK and it was capable of charging 5 coins per play. It definitely was a different time.

Here is a link to an operating manual, which includes schematics and parts list.

https://www.arcade-museum.com/manuals-videogames/D/dk-tkg4u....