The$6T number is per year revenue target in 2031. 6B is a round number, but facebook has 3b monthly active users, and google ai overview has 2.5b monthly active users. baidu (no google overlap) has 644m monthly active users. So at 3b internet connected users addressable or so, its $2000/user. MAUs double count work/personal/multiple/bot accounts.

Also, there's about 1b desk/knowledge workers in the world. = $6000/job/year