2 horses plus chariot is always going to be more expense and effort than 1 horse plus rider, and there are other considerations at play. More can always be said about chariots and their intricacies, so if anyone else would like to address themselves to the topic, please don't let this post stop you!

For the meantime, OP, here are some previous posts on chariots for your perusal:

• u/JoshoBrouwers has an overview of chariot combat in general, which also deals with their fall at the end;
• and u/PM_ME_UR_SADDLEBREDS looks at the reasons for the rise and fall of the chariot.