A better question: why is litecoin better than monero?
Same reason as why bitcoin is better than litecoin. Litecoin is older than Monero, while some people not involved in crypto know litecoin, while not monero.
Well? Let's hear it.
Well, because bitcoin is a thing that earlier than litecoin and its media coverage is greater than litecoin. At least my family which don't involved in bitcoin know about bitcoin in news, while litecoin isn't even mentioned in news... Also SHA-256 hashing is easier than scrypt hashing, so it is more popular...
(If you wanted to start a discussion about this, please start this in Altcoin boards.)