That's not really "wealthy". By wealthy I am talking about at least 100 million RMB or more. It is very hard for a party official to amass that kind of wealth without getting their heads chopped off. They better be very good at hiding or rise to top positions. China executes hundreds of officials each year.
Private businessmen can get there much easier, if they are good at gaming the system. You are right that government officials are richer than ordinary people and are definitely corrupt. But the party core itself is not a club of super wealthy like people imagine here. In fact, the party has an uneasy relationship with the wealthy, many of whom want greater rule of law to protect their wealth.