I mean, I don't know what fraction of that 100M users are Java Minecraft. Obviously Bedrock is entirely up to Microsoft, they can do whatever they want in their sandbox and I'm sure most 5 year olds don't care either way.
On Java Minecraft, which is the only way you can seriously modify the game - I haven't actually run the out-of-box experience for many years, but unless it changed you just pick the version you want from a GUI.
If you play modded more than a tiny "dip my toe in it" amount you run dedicated "launcher" software (I run MultiMC) and that takes responsibility for managing a whole bunch of exciting problems, each of your Mod packs probably expects to live in a separate Minecraft environment, with a specific version of the game, it needs to track whether the Java parameters are special (e.g. more heap, different garbage collection prefs) some people prefer to play some packs in a different screen resolution.
One of the very strange things for a few years was that Twitch (yes, that one) managed this stuff for a lot of players. You've got the Twitch.tv app, which people use to watch say, Ninja playing Fortnite, and there's a tab in there for mods, and then a tab inside that for Minecraft, and that's a valid modded Minecraft launcher. It made some sort of sense because one of the few long term audiences on Twitch is Minecraft, so while there may never be more Minecraft audiences than there are people watching this week's hot new game, by next year that game is irrelevant and the same audience is still watching Minecraft. The tie-in deal that caused this eventually went away though.
On Java Minecraft, which is the only way you can seriously modify the game - I haven't actually run the out-of-box experience for many years, but unless it changed you just pick the version you want from a GUI.
If you play modded more than a tiny "dip my toe in it" amount you run dedicated "launcher" software (I run MultiMC) and that takes responsibility for managing a whole bunch of exciting problems, each of your Mod packs probably expects to live in a separate Minecraft environment, with a specific version of the game, it needs to track whether the Java parameters are special (e.g. more heap, different garbage collection prefs) some people prefer to play some packs in a different screen resolution.
One of the very strange things for a few years was that Twitch (yes, that one) managed this stuff for a lot of players. You've got the Twitch.tv app, which people use to watch say, Ninja playing Fortnite, and there's a tab in there for mods, and then a tab inside that for Minecraft, and that's a valid modded Minecraft launcher. It made some sort of sense because one of the few long term audiences on Twitch is Minecraft, so while there may never be more Minecraft audiences than there are people watching this week's hot new game, by next year that game is irrelevant and the same audience is still watching Minecraft. The tie-in deal that caused this eventually went away though.