Prayer didn't work for Whitney Houston, did it? I am almost sure she was very religious and always had people praying for her to get clean and get her mind right, but it sadly didn't work. Prayers are just words to the wind, not tangible, not real. So why even bother?? To make yourself feel better? HMMMM?!?!?!?
Prayer is a complicated matter, there are so many people with books out on the topic and everyone has different opinions to make it more confusing. "Whitney" more than likely had many praying for her to get clean and get her mind right. If I'm not mistaken, I think she also came from a "church background" and so she probably knew God was there. I'm sure God had/was knocking at Whitney's heart. Ultimately, it was her decision to make as God doesn't make anyone accept Him.
Unfortunately, people don't just get to live on and on until they decide "ok, it's time for Jesus now"...because they never would. Many tend to think that they will just do what they want to do and then they'll get "Jesus" before it's too late. Usually, it doesn't work like that.
A person gets "trapped" and their addictions mess up their minds in such a way that Jesus is the LAST thing on their minds. (If it was hard for that person to seek Jesus when they could think straight, it gets even harder when they can't!)
Just because someone prays for someone else doesn't mean that prayer automatically gets answered with a "YES" from God. God is not some "wish-granting genie". I think "The Lord's Prayer" is a good example of how prayers should be. Prayer is converstaion with God, not just giving Him a "wish-list". They're are all sorts of reasons why some prayers get answered, some don't and some get a "no" which is also an "answer".
There are quite a few people that I've been praying for for many years now and I know God has knocked at their hearts because after I had been fasting and praying for them (without them knowing) they had told me things (like how they had given a hitchhiker a ride recently and it turned out that he was a pastor, and they really liked him and was going to be going to his church...and they did for awhile but then they started messing around with the "addictions" again and that tapered off). That has happened repeatedly with some of them because while I can request that God keep knocking...and God will keep knocking, this person has to open the door and they have to open the door before their number is up to avoid becoming another tragic ending.