So the reason why many artists take offense to the "compliment" of being called lucky is that by nature it undermines a lot of hardwork and effort that is not often recognized by society, peers, and often family. Many artists aren't recognized for thier practice, dedication, and focus. Im sure you are aware its a path that comes with more discouragement than respect.
You're more than free of-course to speak your peace, but instead of telling others why they're lucky, why not focus on the opportunities and fortunes YOU personally have. There are plenty of things we can be grateful for and sometimes when we focus on talents of others we lose sight of that gratitude.
Instead of telling people that they are lucky ask yourself, what could I be more grateful for and how can I use what I have to better my life.
Just a word to the wise