And on top of proving their place they've had to play about 4× as much to get to that point (and probably way more if you count grinding to get into the qualifiers) so it makes sense they get compensated for their time if nothing else.The top 8 get a free ride into the event. They all earn $300 even if they lose 0-3.
Whereas the qualifiers earn $200+$300 as they proved they deserve to be there.