PaladinNO: As said SO many times already, it's because the patches include all the different localization voiceover files.
The alternatives would either be to keep every single supported language separate, which would just create a mess of files to navigate and maintain
Or none of them, and leave it up to the user to download the spoken language they want, Which would create a lot of complaints because some would inevitably forget to download the language files in addition to the rest of the game whenever there is a new patch, and then come here or elsewhere to whine about a mistake they themselves did.
Meh, I would honestly prefer to just have the free space required AND the option to actually use all the voiceover files to freely select which spoken language I want ingame.
It makes no sense that it needs more space than the total install size of the game. 76.8 gb plus 1.5 gb patch shouldn't require the 78.3 gb install size and an additional 85.6 gb of free space on my hard drive. No other installer (Steam,Epic, Uplay, EA App, Larian installer) requires more space for localization files than the entire game