Why is it so easy for some woman?

Alissa • 30yo - been with fiancé for 9 years 💍 TTC baby #1 since Sept 2014 ❤️ 1st cycle IVF w. ICSI: in process!
I don't get it... Why is it so easy for some woman? I see woman post on here things like "my son is 6 months and I'm pregnant again" when some of us (like me) have been TTC baby #1 with no luck, not even a scare. I just don't get it.