Yeah, I bought Forza Motorsport 5 recently and I am really enjoying the game!

Then I saw the rankings list and it shows close to 2M players ingame (with VGC showing 1,4M sold). Could it mean that close to 40% of all X1 owners have bought FM5 and 30% of all sales coming from digital (since VGC doesn´t track digital)?

Assuming 30% of titanfall sales were digital, that could mean somewhere around 2,9M in total sales and a near 60% of all owners bying that game (since VGC shows arolund 2M sold).

What do you think? Am I way off, have I missed something or are these games getting these huge attach rates?

2m is way too high. And that 2m online would be even more players than what the recent COD  games had on the 360 in their first few days of its release. 2m in game probably means something else.   
I agree that it could be under tracked cause of bundles. but I doubt its under tracked by such a huge amount.

When people lend games, buy used games.....

Multi-accounts probably have a big impact on the leaderboards.

used game sales...

but for every used sales there is a seller .

Yep so 1 game = 2 people that have played it = 2 people on the leaderboard

my bad i thought he was talking 2mill online not leaderboard numbers.

This guy got it. 2 Xbox live accounts doesn't neccesarily mean two different XBOs

Both feasible, XB1 players buy a lot of games.