Yes, I agree to a certain extent on the manipulation subject. HOWEVER Ripple opposite to many altcoins is not a decentralized transaction system, it is highly centralised, meaning that the majority of Ripple coin are held by the creators themsleves. When you have a centralized coin and not a highly distributed coin such as bitcoin, the majority of price flactuation depends only on a few actors, in Ripple's case the creators themselves thus its in their interest to keep the price stable