You need to know that of all GTP members here, how many are actively posting in GTS forums ? How many daily members/guest visited the site that reads GTS forum ? I see less than 1000 users or a bit more most of the time daily ( as I typed this, around 900 total, 210+ members and 540+ guest, the rest are robots ).
A lot less than 1% of potential GTS sales In terms of numbers, we are very small compared to the sales number.
Look at me for example, I'm the only garage owner in GT6 that drive exclusively without aids, and do realistic replica setup on cars ... and this is GTP
Most of the GT players are more on casual side, look at Exeter GT tuning garage as example, it's way more popular and received lots more visits on the thread ( 1,345,229 views ), although I may be second to Exeter with 478,778 views ( still less than half of Exeter )
99.99% GT6 players drive with brake assist ( ABS 1 ), and
most casual may struggle with it doing TT and seasonal races ( look at seasonal thread of players doing races and TT, looking for tunes or struggling golding them - the La Sarthe 700PP TT for example )