The challenge of the modern social media. If someone doesn't particularly care for the topic or if there are too many words they just simply move on and don't bother. Sure posts can get decent rewards from people dropping a few votes to it but the engagement is in the toilet with some regards.

I don't take it personally though, when I spend a lot of time on a post and don't get any or many comments where I feel like it could. I just keep plugging away and doing what I enjoy doing.

To be fair though, you say your account is a long-term investment instead of a social place. Many will take that literal and just invest in it and don't bother to check on it. Although I tend to check your posts out every few days, I miss a lot of them because there's also lots of other things to read that I may be more interested in. Nothing personal on you or the project but you have to take into consideration if the content is dry or not something to continually read, people will just skip past it.

If you wanted to get the investors attention, tag them in the post if you need a decision or feedback or something. If I invested in it but missed your post, I would prefer to be tagged in something that you felt was important for me to look at. That's just my personal thought but could work for others.