At first they were 21.co and they invited developers, startup CEOS and investors under the premise of much larger per-response rewards ($100 for investors, $20

At first they were 21.co and they invited developers, startup CEOS and investors under the premise of much larger per-response rewards ($100 for investors, $20 for CEOs, etc). Since then, they've been sending mostly $1-$2 spam from Tokens and ICOs. The payment is in Bitcoin, so cashing out also takes a big chunk of the earnings. Coinbase sounds like a nice landing spot for a team that likely dreamt bigger than that.