First of all, the decision of adopting a child is a tough one. There has to be an actual reason why a person or couple would choose to adopt a child. I like to believe that being unable to have their own children is one of such reasons.
Unfortunately not everyone is capable of having kids. Some people get diagnosed with sterility and despite all medical trials and medication, they still end up not being able to reproduce. I think this the point when adoption becomes an option, especially if the said persons really need kids in their lives.
Some people on the other hand are passionate about adopting kids in an attempt to give them a better life. Some of these people have kids of their own, but they simply choose to help improve the society by giving orphans another chance at life.
Whatever the case or reason, i believe adopting a child is huge responsibility. It's takes a lot of effort and dedication like someone said to bring up a child. It takes a good person with a kind heart to go through such process and treat the child as if they were theirs. If life treats me fairly and I come to a point when I realize I have the finances, can put the effort and have the goodwill, i won't mind adopting a child too.