You’re right that people don’t care, but not sharing your work is not a solution. Sure, you need quality posts, but you need people to actually see them.
If you’re not sharing your work, typically the only way people will find it is through the recent feed or a search. Your suggestion can be viable if you are strategically selecting a topic that people are actively searching for, however it will still never be as effective as if you were sharing your work too.
And when I say you should be sharing your work if you wish to be seen, I don’t mean send it to your Facebook friends — because as you said, your friends really don’t care. Instead, you should be putting your work and name in front of people who do care, without being spammy. For example posting to a relevant subreddit or Facebook group can be very effective (although you shouldn’t simply be pasting a link — this is just blatant spammy advertising).
TL;DR: The phrase “build it and they will come” is far from the truth. You need to be writing on topics that people actually care about and sharing it with people who are interested in the topic.