In October it would have been insensitive unless there was a lot of Tehillim being said. At this point not anymore. Are there no celebrations being held in Israel? No (secular) Demonstrations? Is this a party or a concert for the sake of gorging yourself or a fundraiser to support Torah which in turn supports the world? Is there ANY Jewish group that has completely stopped making events?
If you personally are not listening to music these days because of the war in Eretz Yisroel then maybe you should not have attended. But if you are you have no business complaining about this event