At What Point Do You Stop Trying?

I follow a page on Facebook and it's about a little boy who had passed away recently but originally it was about sending prayers and well wishes to help him get better. I won't share his exact story but just say that his family had gone through a lot. His parents are young, in their early 20s and had a son with a very rare disorder. Before that, they suffered a miscarriage. When they got pregnant with the son they made the page for, early on they learned that he would have problems but then they decided to fight the odds and have the baby who they would love no matter what. He had passed away before he turned a year old after a long hard fight. That was in August. Last month, his parents announced that they were expecting another baby. They didn't say how far along or anything like that, just that they were expecting again. About a week later, they came back on and announced that they had lost the baby.

So here's my question, when you are trying so hard to have a family and obviously having so much working against you- you're under 25 and have lost 3 babies- at what point do you just give up and say " this is enough pain and loss"?

I feel so bad for this family and hit everything that they have had to go through. People that deserve and want to have children can't just have it easy. And yet, people strung out on drugs can have 12 kids and mistreat them their whole lives, The world is not a fair place.. Why can't good people have good things happen?