I guess I'm just confused where you are figuring that 40% of all testers have it? While you claim that about 15% of all Tesla's have FSD beta, you have no idea how the number of TeslaFi users with FSD equals out. There's almost 20,000 users on TesalFi now, and the various FSD versions add up to ~50% of those users being FSD beta users. Which tracks, as if you are nerdy enough to use TeslaFi, you are likely a "buy FSD" type of person also.
TeslaFi shows ~1,300 installs with 156 pending. A normal wide release will have thousands of installs pending.