Taking a look at their signatures, though I don't see any referral links, it could just simply be a campaign for popularity(and obviously to gain token buyers).
There's more shadiness to this than just the referral links. Take a few minutes and take a look at their website (hex.com).
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I would give you the well-meant advice not to do it...
I'm almost sure that there are just some people lurking to tag someone red, on the grounds that you would take part in a scam and advertise it.
In addition, this campaign would be so very unclear to me, and I prefer to not apply there at the slightest doubt
So much money it is now also not. Apart from that, the campaign will only last 4 weeks, I think!