I like to play Howrse both because breeding to increase genetic potential is fun and because I can role play "horse rescue" of low health 0 bid horses from the auction and get them healthy for re-sale (yes I know they may end up in SH, that's fine, I'm role playing).
I'm currently focused on breeding to win rosettes in each English discipline, and breeding these rosette winners and prospects for offspring to train up and sell to sustain it.
I am not considering selling any of the horses in my Favourites tab at this time, thanks for understanding.