The answer are onin the first episode of the series. Only 10.000 000 copies of the game are sold, and, all of them are in use, because onin the presentation, when Kayaba toldstold her all of her the "new rules" hey, there are more than 9k players online, and some are dead at this moment.
Also, iI can understand other explanations are correct, because yes, probably the "login server" areis down, or there's only a hidden server (Norneither series ornor the novel told nothingsaid anything about if Kayaba can logout or not).
@Quikstryke: They cannot hijack packets of the server. I explain: Allall these players are onin controlled environment, because of this, you can sniff the information between NerveGear and the servers. But, you doesn'tdon't know the use of these data. When you do a sniff on aan MMO, you are playing the mmoMMO itself, because. Because of this, you view a packet going to the server or from the server and the effect of this packet on your screen. If you receive a bunch of packets, but you cannot relate it with the proper actions on the game, all these information are more or less shituseless. More, if these information are encrypted. If you have 5 packets, for example, you can try to relate itself with actions (for example doing one more time the same action for view common packets). But, if you have thousands of them, you doesn'tdon't have nothing.