πῶς ἡμῖν οὐχ ἡδέως πρὸς τούσδε τοὺς ὁμοτίμους ἀγωνιστέον
This preposition has so many meaning that it is difficult to chose; it cannot mean ‘against’ here, so then something like for the sake of, would probably do. But the English translation has it as ‘to compete with’, which is not evident to me.
“against” LSJ πρός C.4
yea i agree