Maybe the others were all hoping to be reserve champion. Which is still a huge deal at Indoors, even if they know they won’t be champion.
The difference between fifth and sixth place can be enough to make a horse champion or reserve at a major show, depending on the points, complete with the accompanying bragging rights. So yes, under certain circumstances, many people will think it’s worth the money and effort to take their best shot, even for a low hack ribbon.
Or even if they are not in contention for a tri-color, who wouldn’t want to be able to say they had the hack winner at Indoors?