I highly, HIGHLY doubt Roblox has 50 million daily players tbh, if that's supposed to be unique players. Actually, I'm curious how these trackers or even the companies themselves measure "daily players". Do they mean unique player accounts or just play sessions even if they're from the same account logging on and off throughout the day?
Starting to think it's a mix of both, how they measure daily player count and also lifetime player count. But the way companies market their player count numbers don't make that clear.
At least in the company side (I worked in F2P GaaS games) daily players are measured as DAU, daily active users. It's the amount of unique users who played the game at least once in a specific day. If a player logs in multiple times on a day is only counted once.
There is a separate metric that is the average amount of daily gameplay sessions per player, and another one the average length of gameplay sessions. There are other metrics like ARPU (average revenue per user), ARPPU (average revenue per paid user, same as before but in a F2P only counting those who paid), average amounts of hours played, LTV (life time value, average amount of revenue generated by a player since starts to play until finally leaves/quits the game for the last time) or retention (D1, D3, D7, D15, D30, D90, D180) which is the percentage of players that continues playing after this amount of days. Meaning D1 is the percent of players who come back to play after the first day and D30 the percent of players who are still in the game after a month.
Every single company with a GaaS/F2P/online game tracks internally metrics like these and a ton other more, because they are helpful both to compare the performance of a game against other ones, areas where they have to improve, etc.
In games with DLC and microtransactions a very long retention is key because on average the more time you spend in a game the more likely is that you may end paying for a DLC or microtransaction. This last bit is key for F2P because only a very small percent of their players pay something in the game.