why would an owner do this?

[ontheoutside]

look, 1st off, i have no clue as to how the bisiness aspect goesas far is my question is so please,, dont fire at me,, ,,educate me

my question is ,,why would the owners be autioning off midnite bysou?
some people say she mite fetch 4 million

my thinking is the horse is 4 years old,, she could be a mama for 12 to 16 years
im sure the owners are not hurting for money,
so why wouldnt they take the babies for the next 15 years and tsake there chances with a great moms babies?

thanks