I get that (and updated my post to qualify with "Orthodox"); that's not really the point. I of course am aware of many people who joke they're "the worst Jew ever" and such like that, because they identify with the group, but don't practice any of the religious aspects.
But that's not really the point. There exist people who do strictly follow the religious aspects, and that's what I'm confused about.
Specifically Orthodox Judaism. Most Jewish people (at least the ones I know) don't bother with all that stuff.
Same as Christianity, there are a lot of non-religious Jews. They follow Jewish culture (e.g. holidays, cuisine, and tradition), but don't adhere to strict dogma. Most of my Jewish friends will eat pork if you offer it to them, even if they wouldn't usually eat it at home because it's not a cultural norm.