High pay of cash? I haven't seen any bounty that paid their participants in cash. Most of the bounties that existed before and until today are paying with their own tokens, if not with those it's either ethereum or bitcoin.

And being a bounty manager isn't an easy task, yes it may seem to be the best but hardwork is required and building your reputation is also hard to do. That's why most of the reputable campaign and bounty managers are well trusted and respected here because they know what projects to accept and to deny.