Several things:

First, I'm thinking of when Q apparently announced the taking offline of several CIA supercomputers and spy satellites, Q posts 2008-2021. It seemed this was almost simultaneously announced by Hal Turner. I think Q posted first, based on time stamps, but I'm not sure. Turner did not cite Q as a source as far as I saw, but a lot of the key phrases were the same:

http://halturnerradioshow.com/index.php/news/u-s-national-news/3079-7-cia-mainframe-super-computers-down-spy-satellites-offline

Hal Turner seemed to be citing additional sources in later updates, but who knows for sure. I haven't found any other independent confirmation that this takedown actually happened. Articles elsewhere seemed to be quoting Q or Turner.

Secondly, there was MegaAnon. She maintained for a couple of months that Q was a LARP, with the possible exception of the first few days at the end of October. But at some in January she suddenly changed her mind and decided Q was for real, because Q was doing things which in her opinion only someone with high government access could do. Very shortly thereafter she stopped posting altogether. Some people thought her reddit account must have been hacked and someone was pretending to be her. However, both before and after this, she had phone conversations with David Wilcock who verified that it was the same person.

Thirdly, I've been wondering if it matters all that much if Q is a LARP, because the Q posts seem to have woken up a lot of people, a stirred up a massive overreaction among the mainstream media to try to debunk it, generating even more awareness. So even if it started out as a LARP, it may have evolved into a public service, of which perhaps even the Administration may now approve.

We shall see.