Short answer is rust, long answer is red tape.
Many patents in the hands of CAT and shelved as they own Bosch who manufactures and/or gets paid for the "common rail" diesel injection system on almost every diesel engine made in the west.
Bitcoin price dropped 4k in 8 hours and still plummeting.
Imagine making 4,000 dollars in hours.
Now imagining losing it, multiple times over,
Ouch.