Considering he died flying a planeload of explosives out of which he was supposed to bail before it was crashed into a Nazi target that plan did not work out very well. One can criticize the Kennedy clan for countless things but Joe Jr. and Jack did serve. Did they do so to prep their resumes for Papa's dream of a presidential son? Maybe. Scum bags? In Jack's case as far as his treatment of his marriage and women in general? Certainly. But they did go into harm's way when a lot of others didn't but still used the uniform as a campaign tool (thinking of LBJ - perhaps JFK's womanizing equal and a far bigger SB).
Well, kind of, but not exactly. He was supposed to jump out when the aircraft reached the English channel and be back for evening cocktails. Unfortunately his co-pilot took an action which caused the aircraft to explode. Yes he did die in the service of his country, but no it was not supposed to be dangerous.
As far as JFK was concerned, he was safely serving in the Navy - in London - in an office, thanks to string pulling by Joe Sr. Unfortunately, as would be typical of his life, JFK started fooling around with a woman who it was suspected might have been a spy. To avoid a scandal, he was rushed to the Pacific before Joe Sr knew about it and could pull any strings. So he too served his country, although a lot of it was by accident as well.
It had to really hurt Joe Kennedy Sr’s feelings knowing that Jack died fighting Joe’s Nazi pals. Joe wished if he had to die in battle it would have been against the British.