Bitcoin doesn't even have 1 million and has had multiple problems with forks in its long history. NEM has 2 million and is just fine.
I'm not sure, if this is correct comparing - a/ NEM has 10 times faster block generation, b/ utilization of BTC blockchain is much, much higher than by NEM. Hopefully this will be change sometime in the future, but now it looks really bad (and we're constantly falling, now at #18 position on CMC).