You don't need 5 million, that is just the number that would be optimal.
It's not like it's going to be a situation where 4.5 million won't be enough. It's just what Makoto said he would have, knowing what he knows.
They are not about to say, "surprise, you only have 3 million so your out!"
Hope so. Otherwise i would be a little disappointed.
ps: NEM is almost my last hope in crypto....