Many bounties have already says it all in their rules and regulations that 'THE BOUNTY MANAGER HAS THE RIGHT TO CHANGE RULES AT ANY TIME' when you see something like that always know that anything can happen ,the one way to avoid this is if there is no such rules on the bounty thread.
Bounty hunters still find it very hard to read,they care less about rules and go for the good looking bounty allocation, please have patience and go through rules and regulations ,most times its not always the bounty managers fault.
So I think bounty and investment, we have to take risks, we invest our efforts instead of investing our money.