As indicated by the deliberate use of the word "adjacent", it's a sign that the crypto space and the alt-right have sufficient contact that there is horizontal memetic transfer (in both the original and modern senses of "meme") between the two.
And considering that Richard Spencer himself called Bitcoin, "the currency of the alt-right" it's not surprising if there's cultural cross-pollination.
For example, pretty much everyone I hear saying this word is a liberal. But that says more about who I spend my time with than who uses the words. It has more to do with being Extremely Online than with any specific political affiliation.
P(alt-right|fren) = P(fren|alt-right) P(alt-right) / P(fren)
You have tunnel vision for P(fren|alt-right) and are confusing it with P(alt-right|fren).
But it probably isn't. It's a cutesy term adjacent to pet-speak and baby-speak. Do an image search for "frens" and most of what you'll find is cute animals, 10-to-1 vs frog cartoons.
https://www.reddit.com/r/aww/comments/uyhno1/frens_chilling_...
https://www.google.com/search?q=frens&tbm=isch
Very wholesome.
The alt-right has a meme of 'appropriating' popular terms and symbols in an attempt to make people overestimate P(alt-right|symbol), to make their critics seem unhinged as they level accusations against innocent people, and to make themselves seem more popular than they actually are. They've done this with 'frens', the 'okay gesture', and even drinking milk. You have unfortunately fallen for this, and become their tool.
The same search on Google gives me pretty much nothing but Pepes - only 7 images in the first 30 results are not Pepes. Google is pretty convinced "fren" is an alt-right signifier.
1: I am proposing "duckwent" as the past tense for "duckduckgo".
That's a nice theory, and until a proof has been constructed, presented and validated it'll keep being a nice theory.
It's just dopey Internet slang, like lulz and omgwtfbbq, and alt-right (whatever that means) is also an Internet thing.