I'm already level 62 and have reached prestige level 3. Reaching level 100 requires 50 million XP. I finished the previous game with around 48 million XP and was ranked around 1800 on the leaderboard. This means only about 2000 to 3000 players at most will ever be able to reach it.

For addicts like me, there should be a "hall of shame" leaderboard that keeps counting XP even after reaching level 100. The game is already lacking when it comes to stats anyway; at least this way we could know exactly how much we've actually played. As you know, the standard playtime tracker doesn't subtract AFK time.