Boost the reach of your posts with comments
Comments below your item can help you sell your item even faster, because it makes other buyers aware that there are a lot of people interested.
There is also another big advantage, and its how the Instagram feed works. If a post has a lot of engagement (comments), it will reach more people and stay on top of the feed longer. Therefore, as a seller its important to reply to comments of potential buyers, in the comment section.
Or if you want to help a friend, you can leave a small comment below his/her post and bump it to the top.
Below, you can find an example of a pair of Balenciagas, recently sold here. The seller answered to all the questions and ended up selling the shoes. The post generated over 200 likes and 16 comments.