We know if you make dolphin you wont leave so the more the merrier.
Most of the dolphins that make it do tend to stick around but it isn't the Steem, it is more likely that they have built a good understanding of the way the platform works and, could work.
That makes perfect sense as it takes time to learn. Becoming a Dolphin normally means a lot of work has gone into getting there and the account may mean more than just monetary value.