Yea, that's true.
Are you arguing that they should give them a high-five for forsaking how their parents raised them and accepting the western, white man's way of life?
I too would be upset if they left the truth and full-sale bought into their own destruction and ruining their aakirah.
It's the same as getting upset at your kids for following any other bad habit. The problem lies in you thinking it's okay to leave Islam and akin to changing your lifestyle to become vegan or quitting school because it's not for you, etc. It's not something that's light.
Also, Secular Christians and Jews outnumber those that still actually practice their religion devoutly. When your entire family already doesn't attend church regularly, commit pre-marital sex, eat pork, consume interest, divorce, consume ography and dress immodestly casually, get drunk, etc, etc. Then it's not a crazy thing to take one more step and stop identifying as Christian or Jew, it's basically verbalizing your actions because you already don't practice..
You can't compare Muslims with Christians and Jews because for the most part we don't practice the same. They've made their religion symbolic and not something they live by.
But, this does remind me of a hadith:
Abu Sa’id al-Khudri reported: The Messenger of Allah, peace and blessings be upon him, said, “Verily, you will follow the path of those before you, step by step and inch by inch; if they entered the hole of a lizard, you would follow.” We said, “O Messenger of Allah, do you mean the Jews and Christians?” The Prophet said, “Who else?”
Source: Ṣaḥīḥ al-Bukhārī 3269, Ṣaḥīḥ Muslim 2669