When good advice isn't taken:

its true its true

For some people it is important to make the mistakes personally to learn out of it and for some people even that will not change their mind

People will always do what they want to do. Most times, when we ask for advice, we're just asking for someone to reaffirm what we think, so if we fail we don't feel as stupid because we weren't the only ones who thought it was the right thing to do.
A friend of mine was trying to buy a SUV a few years ago. Good looking vehicle, good price, a little too good to be true. The dealer was my neighbor, by coincidence. I asked my neighbor about the SUV's real conditions. He said he didn't know, and didn't really care as the vehicle was given to him by the owner to sell with the instructions to sell it quick. He made it clear to me he was not going to be responsible for any problem. I told this to my friend. My friend made up a hundred reasons why it was still a good deal. I offered him the assistance of my personal mechanic. The mechanic checked the vehicle and said it had serious transmission leaks, affecting the 4x4 function and eventually affecting the whole transmission. My friend ignored this, even implied I had told my mechanic to say this because I didn't want him to get that great vehicle at such a great price. Fool. Needless to say, he bought the truck, which failed before a month had gone by. Needless to say, we're not very good friends anymore. Lesson learned! Never try to change your friend's mind, specially if he/she is fixed on the idea (hello sankies!). Let them make the mistake, and just comfort them and help them recover from the failure afterwards.