Since that contest was mentioned only in this forum and mainly on that particular thread, this didn't get much attention, but if this were a larger scale event, there would be legal repercussions against a sponsor backing out like this, and also going forward all the funds should be secured by the organizer long before the event is concluded for the benefit of the participants...
If I am not wrong, I have seen some content in this forum where every time participant has to pay fees and they had to pay it before they join. The organizer make sure they receive the funds for the prize pool. Even the sponsors send the funds to the organizer most of the time. I did not check some contest if sponsors paid the amount already or not. But what if Rollbit or Sportsbet denies to pay the promised prize? Wouldn't you guys leave them a tag because they were suppose to pay the prize. Isn't it same like a person promised he will pay if I win, now I won, but he said he won't pay me. I guess it's same. The difference is, the corrent contest isn't ended yet.