I'm going to tell someone their problems are their own fault
Why do you want to tell them that about their problems?
I'm going to tell them that because their life sucks and they're the only one who can change it.
Even though you are just telling them that so that they have a chance to fix their problems, it is not nice to tell them that it is their fault. It will make them feel bad and it would make them upset with you.
I'm going to tell them that everytime they ask me for help. I think they should take care of themselves.
People do not usually make people feel bad about their problems and that is what will happen if you tell someone their problems are their own fault. You should choose your words more kindly.