People who have played the game directly correlates to popularity....
Sure, but without knowing how many players GT7 has in general, its premature to say FH5 has surpassed it based on overall players. Take Uncharted 4 for example, with its last official update being 16M - 17M units sold in 2017/2018, it has been confirmed to have over 37M players. I wouldn't be surprised if UC4 overall player count is well over 40M now that its on the PS+ Collection.
Also, Fortnite and Apex Legends are out FH league lol. They shouldn't be in the same sentence when it comes to popularity.