I know nothing on the topic but why would one use bitcoin to buy drugs? Aren't all bitcoin transactions public and immutable?

Yes but they’re also anonymous. You don’t have your name attached to the account and there’s no paperwork/bank that’s keeping track of any large/irregular financial transactions

So, exactly like cash?

Yeah, exactly, but with the energy requirements of a small country to run the network.

No, not exactly. If you know someone used cash at one place can you track every cash transaction they've ever made? If you know one bitcoin transaction from a wallet you can track everything that key pair has done from genesis to present. So, if anything, it's worse.

Not quite because there are logistical challenges to moving large quantities of physical money.

I heard this as one of the early sales pitches for Bitcoin. “Digital cash.”

That all seemed to go out the window when companies developed wallets to simplify the process for the average user, and when the prices surged, some started requiring account verification to tie it to a real identity. At that point, it’s just a bank with a currency that isn’t broadly accepted. The idea of digital cash was effectively dead, at least for the masses who aren’t going to take the time to figure out how to use Bitcoin without a 3rd party involved. Cash is simple.

They're pseudonymous. Not anonymous. Big difference. Monero transactions are anonymous.

Bitcoin failed because of bad monetary policy turning it into something like a ponzi scheme where only early adopters win. The monetary policy isn't as hard to fix as people make it out to be.

I came from the other end: I had years to get on the boat and missed it.

I couldn’t fathom what use Bitcoin could possibly have, but completely overlooked the bad actors that would benefit.