It wasn't a dumb question. There are two different thicknesses of 2.5" HDD. The 9.5mm fits properly, and the 12.5mm requires (slight) physical modification of the PS3. Many (most?) of the larger capacity drives are 12.5mm.
Disagree: to have or express a different opinion. It's not hate and it's not trolling - it's simple disagreement. Quit crying.