Their "gaming platform" was on the same level as early Facebook Games, except a decade too late -- little dinky HTML5 games you could play in group chats. It was never going to be a major source of profit even if Apple hadn't blocked it.
The fact that something is free to you does not mean no one is paying.
Telegram is also open source.
I don’t know if you are seeking to counter my point, but open source seems orthogonal to expenses associated with maintaining infrastructure, ongoing development, reviewing massive amounts of UGC and so on.
I was under the impression you were trying to indicate that just because Telegram is free, that it's users are paying one way or another. However, agreed that Telegram does end up paying for backend costs but the app could be modified to utilize a different backend.