In the near to mid future, I think an answer to this question are Internal Combustion Engines. I love electric vehicles and look forward to the tech improving. But the sheer coolness factor of moving a large machine through perfectly timed and calibrated explosions is tough to beat.
It helped me tremendously in college, and I still use it today, both for past knowledge retention, as well as learning some new things. It is an incredible tool.
As far as the learning curve goes, I would recommend this: just use it as is. You can dive down a rabbit hole of optimizing your learning approach and adding the right extensions, but that time is better spent just studying what you want to learn.
Use the Cloze format, keep cards limited to a couple sentences at most, and practice daily for a couple minutes, and you can’t go wrong.