First of all, Myrtle belongs to a different class to the others: she is seeking to escape from life in The Valley of Ashes, the flipside of the attractive wealth possessed by the others. Therefore, she can't be placed with them so this Q. and A. will only deal with Gatsby, Tom, Daisy and Jordan.
Tom, Daisy and Jordan are all characterised by their carelessness. Jordan is a careless driver who relies on others to be more careful to avoid accidents. Daisy is also careless;just as the love triangle is coming to a head Nick remarks ' (Daisy's).. got an indiscreet voice' to which Gatsby replies 'Her voice is full of money'. The suggestion here is there is a link between money and careless behaviour. Later, this point is made more explicitly: Nick contemplates Tom and Daisy's culpability for the tragic events:' They were careless people, Tom and Daisy -they smashed up things and creatures and then retreated back into their money or their vast carelessness.' This makes it seem like money and carelessness go hand in hand; Tom and Daisy have 'smashed up' Gatsby and Myrtle - now both dead - their own lives, their own wealthy lifestyle completely unaffected.
It is this kind of behaviour which Nick tells us at the very start 'has closed out my interest' in people. He's disgusted by the behaviour he has seen from the rich people in the book. However, Gatsby is 'exempt' from this judgement. Why? Nick does not entirely approve of him; at least some of his wealth is apparently beased on 'dodgy dealings' with the likes of the gangster Meyer Wolfshiem. So what makes him better than the likes of Tom, Daisy and Jordan who have at least acquired wealth through legal means? It is because Gatsby possesses something the others don't, namely a 'romantic readiness' meaning his money is only a means to an end: Daisy. He's not like the others for whom he has only scorn left.