I agree! I'm a computer architect, and I love playing around with FPGAs for doing 'fantasy architecture' projects (like a 16-core Z80 laptop, or a USB adapter for an old nCube supercomputer). A modern FPGA is like being able to tape out your own 350-nm chip for <$100 (and in many respects much better, when you get to make use of hard-macros like SRAM or PCIe/DDR controllers).

.. not really? They're pretty niche and outperformed wildly by actual hardware.