Perhaps greatest enemy, but I would also argue a false enemy. Even if something better does exist, it would have to come onto the scene with a similar level of infrastructure to compete with Monero. Hell, monero is better than bitcoin, but we're still contending with it's five year lead and subsequent infrastructure and perceived momentum. Thus, it is important for development to get a little gas thrown on the fire, thus why more community funded developers would be great. Our poor cow is working so hard.