Thankfully are jobs will be getting easier as speech recognition continues to improve. Some people start from scratch, some people find existing hard subs and translate them to soft subs, some people just translate subs, etc... some people are prolific but the reason it seems most media has a sub is that there are millions of interested and capable people out there, so if a movie is only meaningful enough to only one person out of say 40 million, that's still one person who will make subs for that movie. We have the countless masses to thank, even when sometimes the quality isn't perfect.