Flatmate issue

Hi I was just wondering if anyone was in a similar situation or had any advice but this year obviously was hard to meet new people so me and my closest friend at uni found 2 new people to live with next year. We have now signed the contract and stuff and 1 of them has turned out to be a really selfish, rude and horrible person. And the other 1 doesn't seem great either. I've tried to suggest the other 1 be replaced as he was last to join the group and some people are still looking for flatmates but everyone has said they're happy to just go 1 more year through this and for third year hopefully to be better. But that means 1st and 2nd year won't have been the best then. And I don't get how people are so happy/ quick to ignore red flags. Hope this isn't confusing, thanks for any advice/ responses in advance.