secular culture - Is it okay to skip a bar mitzvah?

In the popular TV show Arthur, there is an episode wherein Francine Frensky, the Jewish girl, faces a tough dilemma - going to her cousin's bar mitzvah or helping her team win a game. Alan (aka "The Brain") points out, "It's more significant than that, Francine. To truly you understand, you have to go back to the beginning of the Jewish people, when Abraham and Sarah begat Isaac, who begat Jacob, who begat Joseph, who begat-" Then, Francine makes a deal with her friends that she's going to switch back and forth going to the bar mitzvah and going to the game.

Is it okay to skip a bar mitzvah? Are there serious consequences for participating too much in the secular life?

Answer

You mean whether to not attend a friend's bar mitzva?

If the friend's bar mitzva is at 10AM on a Sunday morning, and you really love your weekly baseball game at that time, so you go to earlybird prayers at 7AM that morning, then go to your baseball game -- well it's between you and your friend (or your family, or their family), would your presence at the bar mitzva make a difference. From the standpoint of Jewish law per se, it's all pretty neutral.

Now if "attending a bar mitzva" means observing Shabbat and praying, and "going to the game" means doing neither, then you should "attend the bar mitzva" -- but the same would apply if it was just regular services that week at synagogue, no event going on.

In a broader sense, though, yes Judaism is able to adapt to a degree to the outside culture, but there have to be boundaries! (See here for more.) The TV show was trying to give a nice example that would be palatable to a broad audience. (Assuming this was on a Saturday, driving back-and-forth between events would be far worse than driving and staying at either one, as the act of driving is forbidden to Jews on Saturday.) A better example would be, as indicated in the linked answer, Rabbi Joseph Dov Soloveichik's practice of giving his Talmud lecture earlier than usual on Thanksgiving morning so he could fly to his sister's to attend Thanksgiving dinner. Skip the dinner? No. But skip the lecture? Also no.