If you have a Real estate Project; Shall you make the Marketing with your team or through External marketeer ?

Depends not only on your goals but also on how qualified your team is

This is not mandatory that marketting will be done by in house team  only,any person or entitity can be engaged for this .,hence it is immaterial for a subjective or objective matter i.e real estate .Any thing can be done for sales promotion but above all organizational interest should be taken into account.

If you already have a merketing team why would you bother with the additional cost of the external marketer!

If I work for a real state developer, I will use its marketing. If I work for a contractor, I will use and third party marketing services.