It looks like miners, it could also possibly be a trader - buying outside of the exchanges or steem for less but giving the person tangible cash instantly.
It could also be they were an early adopter and made multiple accounts and invested some btc on each and are transferring it all to themselves.
Hard to say, too late for me to do in depth looks at each account currently though.
ok should i delete this post then if they're most likely legit?
I would keep it just for the sake of maybe someone coming along and verifying one or the other