Hi, selling points or trading them falls into the gray and no so gray side of the Marriott Rewards Terms and Conditions. Even if you had the points transferred the person doing the transfer would need to be vouching for you, and might put their Mr account at risk.
Here is the language on transferring points:
This Member benefit is available only at time of Reward Redemption (only one Reward request per Reward Redemption, please).
Immediately prior to Reward Redemption, a Member may authorize the transfer of the necessary number of Points into the Rewards Program account of his/her legal spouse or domestic partner, in order to qualify for a specific Reward.
Another rule is that solicitation (which this might be considered) is not permitted on Insiders.