It’s not only bitcoins. It’s other named things, as well. From 538 Significant Digits (and it’s funny, especially if you’re a criminal or criminal wanna-be):
$349
In the final two months of 2017, the price of the cryptocurrency monero quadrupled in value to $349, and is up a further 7 percent this year. It grew faster than the top cryptocurrency, bitcoin, which is saying something. Criminals were once a core customer base for bitcoin, but as people have gotten better at tracing where the currency comes from and where it goes, it’s fallen out of favor. That’s left an opening for monero — which encrypts recipients’ addresses — to scoop up that core crimedoer demo. [Bloomberg]