If you have a forum with 100 people and your opinion is downvoted by 50 your opinion is (within that forum) the minority opinion.
That doesn't necessarily mean this opinion is a minority opinion in the real world. In fact it doesn't even have to mean those who downvoted don't share your opinion, they might have downvoted you for a heap of reasons (maybe you were rude, or they saw your comment as pointless, maybe they downvoted every comment except their own, etc.)
Then you might be in an (possible, but unlikely) edge case scenario and should applaude the complexity of reality surrounding us.
The truth is, you can never be sure if your opinion is minority or majority within any online forum just by looking at up/downvotes of one post in isulation.
These are not minority opinions, but unpopular opinions. Just because something is downvoted to hell and hidden, doesn't mean it's a minority.
A minority opinion is one which few people have, not one which is downvoted by the majority.