It sounds harsh, but you cannot fix their problems. I know what you mean as sometimes the solution to someone's problem is so obvious to everyone except for themselves. It is so tempting to rush in and start fixing things for everyone.
I have found though that unsolicited advice is generally ignored. If someone asks you for advice e.g. 'what do you think I should do?' they might listen to what you say. However it is never a good idea to go charging in telling people what they should or shouldn't be doing.
It is sooo hard to step back, but it has to be done. I actually realised I was throwing myself into solving my friends problems because I didn't want to face up to my own. In fact when I took a step back, my friends started doing things off their own back! One friend who poo-pooed the whole LOA a couple of years ago, called me to tell me she has just watched the Secret and manifested a $4k bonus this month.
Have a look at what is irritating you about these people that need personal development, then take a long hard look at where that issue shows up for you in your life. Sometimes the truth is a little closer to home that we find comfortable to admit.
(I'll give you an example, there is someone in my life who is really negative about work which annoys me, but when I look a bit closer she is just voicing my own concerns about my work situation. I need to deal with the negativity in my own life rather than rushing to fix the negativity in hers).
The best way you can help your friends is to be a shining example of personal development. Then a few months down the line they will be asking for your advice about how you lead such a brilliant, fantastic life.