Plagiarism or Copy paste and mix with own words:
This isn't plagiarism, clear cookies stated the source at the bottom, Trying to get revenge by editing the quoted post to frame OP won't work.
"colossal pump-and-dump scheme, the likes of which the world has never seen."
I think this is non-sense, what about you?
Source: cnbc
This guy reported my friend with incomplete proof and got banned. There's no wrong in reporting plagiarism but make sure you provided the whole proof not just the topic he copied.
OP's report about your friend wasn't incomplete. Even if the copied text was only a portion of the post, without the source it's still considered plagiarism. I've reported tons of users who only copy a sentence or two from others to make their post longer then use their own words or sometimes mix it to hide their trails.