Aside from YouTube Red, YouTube is a free service, and so it’s a different sort of competition for Netflix.
That said, the folks at Netflix probably aren’t too worried about how many more total viewers YouTube gets per year.
Netflix is a Subscription Video On Demand (SVOD) service, which means that users have to pay to stream its videos.
Yes, Netflix would probably love to be the leader in total users, but I imagine that the head honchos over there are probably happy enough knowing that Netflix is still well above other SVOD services like Amazon and Hulu.