It is probably extremely rare for anyone who takes a position on a subject to change their mind. On the other hand it gives the people who haven't made up their mind information they can use to make decisions.
Usually the only time I change my mind is when I'm doing research to prove my point and find out from the research that I was wrong.
Then again there's the times I disagree with my wife. Then I'm wrong by definition.
The other thing we should remember is that many times no matter how passionate we are about a topic we are only stating opinions.
I must have listened at some point because I find myself giving the same advice I got a few years back, including some that I ignored at the time.