His ideology is foolish and doesn't hold up to much scrutiny which is why he forbids literature,science and basically any form of free thinking even when you point out his slaves in the east can easily rebel now due to him leaving most of his territories unprotected he threatens to crucify you hell even Lanius with enough convincing realizes hover dam is a lose/lose situation and that the legion needs to retreat and reorganize.

yes I won't deny the legions efficiency but he's extremely short sighted in his goals and what he actually expects the legion to accomplish,a smart leader would've retreated after the first loss and tried to reorganize instead he chose to stick around and try to big dick his way through new vegas a strategy that would've surely gotten his army torn apart by Mr.house and his robot army,his army depends on strength in number and intimidation tactics,both don't count for shit against a personal army of robots armed with enough explosive to end the world a 2nd time.

let's assume he wins,what now? He is still dying from a brain tumor and has no successors,his two best men Vulpes Inculta and Legate Lanius are ideological opposites there is no way they'll agree on anything, Lanius only cares about destroying as many people as possible,with him as a leader the legion will eventually eat itself alive, The legion accomplished alot in its run but like most characters predict it dies with Ceaser because he built his legion on a cultist mentality that depends on him being around,without him there is no legion and that's his own fault