"What does Boosting Your Post Actually Do?" - SocialRefresh.net
What does Boosting Your Post Actually Do?
Booting your post only targets your followers and the friends of your followers by default. It’s also only boosting your post through reach, trying to get your post in front of as many people as possible. That might sound good at first, but you’re paying people to only see the post in their feed, not actually interacting with it in any meaningful way such as clicking on it. So even if someone quickly scrolls by your post not really even glancing at your boosted post, you’re paying for it.
That's the default function of the boost button. To get the most benefit from it you’ll need to sit there and select all the right options to get your post in front of the people that matter. However, the options are limited to what you can do.