Who is “you” in this case? Is you the Roman state or is you a random noble trying to curry favor and glory?
The former supported cavalry because it won battles but the latter did so because it earned them prestige among their peers. It also helped them feel powerful when they rode into battle literally hoisted above the common foot solider, as if they were closer to the gods.
There's a notable technological divergence between the Roman and the noble - stirrups that make cavalry charges possible. Roman cavalry were usually lightly armed and armored and had a very different function on the battlefield.
The former supported cavalry because it won battles but the latter did so because it earned them prestige among their peers. It also helped them feel powerful when they rode into battle literally hoisted above the common foot solider, as if they were closer to the gods.