There are several reasons why making a social media post only saying "Hi!" is generally not a good idea. Here are a few arguments:

Lack of context: Without any further information or content, a post that just says "Hi!" doesn't give any context or meaning for other users to engage with. This could make it difficult for others to respond or continue a conversation.

Low engagement potential: A post with only "Hi!" is unlikely to generate much interest or engagement from other users. In order to spark a conversation or engage with others on social media, it's usually necessary to provide some sort of interesting or thought-provoking content.

Risk of being seen as spam: Depending on the platform and the audience, a post that only says "Hi!" could be perceived as spam or a low-quality attempt at engagement. This could damage your reputation or credibility on the platform.

Missed opportunity to share something meaningful: Instead of simply saying "Hi!", it's usually more effective to share something meaningful or relevant to your audience. Whether it's a personal update, a piece of interesting news, or a thought-provoking question, providing some sort of content can help you connect with others and build your online presence.

Lack of originality: Finally, a post with only "Hi!" may be seen as unoriginal or lazy. In order to stand out on social media and build a following, it's important to provide unique, valuable content that others can't get elsewhere. A simple "Hi!" doesn't necessarily meet this standard.