National Healthcare

Just asking, why are so many people against national healthcare? I admit that I haven’t followed the issue as closely as some others. I have seen a lot of negative comments from people but not any specific reasons – please, no negative comments, I’m truly asking a legitimate question looking for answers. I have experienced national healthcare twice in other countries with great results. Please, once again I’m asking for legitimate concerns, not negative comments. We are one of the wealthiest countries in the world, why can’t we provide healthcare for all legitimate residents?