Moneybags is a jokey name for someone who has a lot of money. You say it to tease, not to bow. “Here comes old moneybags” means “here comes the rich one,” with a smile or a little sting. It is informal and humorous; it would sound odd in a serious article, unless the writer is being playful on purpose. Though actually, it looks plural (bags) but names one person, and we still say “that moneybags is…” as if it were singular. It pictures someone whose bags are stuffed with money. It can be warm (a rich uncle) or slightly unkind (someone flashing wealth). It is not a job and not a polite title. People also use it for a character who is all wealth and no name — a type, not a real introduction.