In  my current perspective it's not illusionary and I find in my direct experience that understanding this concept is very useful tool for survival.  For example, I can eat a healthy meal and feel good afterwards or I can eat a unhealthy meal and feel very bad afterwards. I can exercise consistently and reap benefits from this or I can negate it and my health will suffer from it. I can meditate everyday and be more "woke" on day-to-day basis or I can negate it altogether and see how I splurge into unconsious patterns.  I can go work hard on my money situation, do proper marketing and potentially get good results or I can do 0 marketing and negate business skills altogether and i'll have a good chance that nothing will happen and I'll find myself buying cheetos living in my mum's home just for the sake of symbolism and metaphorically giving credit to Leo.

I've never been as conscious of these Cause and Effect dynamics as I am now. It seems that your Actions have Consequeces  and it feels very real from the ego perspective. What you're doing today determines where you are and who you are in the day\week\year\5 years from now. 
I found contemplating it and being conscious of this very profound. But recently you said that this is an illusion without much elaboration and it got me confused.   @Leo Gura