You can't really download games from PSN at anywhere close to that speed anyway. I have a hardwired gigabit connection to my PS4 and I'm lucky to hit 100Mb download. It's a similar story with Steam, when the stars align it might hit 500Mb for a minute right before finishing, but it usually hovers around 100-200Mb too. It's also much faster than the speeds of rotational hard drives, so unless you keep HD video on SSDs, it's no good for that either.
Beyond speedtests, the only way I can realistically saturate my internet connection is through S3.