For example, both Final Fantasy XVI & STALKER 2 take up 152GB & 165GB on my 2TB external SSD. I mean, why are steam games HUGE as f*ck regarding their file sizes lately? Don’t even mention CoD (200GB?!), even with the fastest internet connection: you can’t bypass patience as these things take up time. For me, it took me about 2 days to finish (pause & resume download). I’ve finished installing KCD II (Royal Edition) and that was 85GB (took up 8-12 hours with fast internet, I was binge watching a TV show on Prime Video the entire time).
Lack of optimization, and crazy texture packs
Audio is another big one. If you want good quality music and your game is voice acted you would be surprised how much space all those audio files take. Add in tons of other gigabytes if you offer voice acting for other languages.
They optimized for things other than install size. Optimization is often choosing one thing at the expense of others.
And a huge number of art assets in general. These days in the AAA industry the artists work much faster than the designers and programmers, so by the time the designers and programmers have finished their part, the art team has had time to make 3-4 times as many assets as they really need.