I thought the community admin needs to accumulate SP to support his community members....

you are right about this. the steemcurator01 and booming support are supplementary only to support the main community curation account. The creator of the community or admins should find a way to become self-sufficient as they won't be supporting the community forever because there are a lot more communities emerging on Steemit that need support in their start-up.. Have a nice day to you too.