When one tries and fails, one has gained more knowledge than the one who has not tried at all. The person who has tried, will instead possess a greater understanding over the one who has not. However, that person must have tried his best in order for this statement to be applicable. Therefore, i agree with this statement provided that the person has tried his best.
Firstly, in the process of learning as we grow up, we face different obstacles and challenges as we work towards our goal or dream. During these times of difficulty, we tend to stop in our tracks. Not many people would continue persevering and move forward to take their best shot. Even if we fail after trying, we would be able to realise the mistakes that we have made. As compared to not even trying at all, failing will benefit us in such a way that we can keep on improving ourselves to become better. In short, we will be able to learn from the mistakes that we made the first time we tried and failed
Secondly, not trying at all will leave you with greater regrets than trying and failing. When you grow older, the amount of regrets for not trying would pile up. As you think back into your past, those regrets could have actually turned into valuable experiences. At least when you try, you attain new knowledge which will help in your future endeavours. The knowledge and experience you encountered could mean the difference between tasting the sweetness of success, or the bitter taste of failure.
On the contrary, In some circumstances, it is better not to try if the end result is obvious. For example, it is a futile attempt to try and woo a girl that does not like you in return. In this case, trying to do so will just lead to disaster. Moreover, you may end up losing a friend, embarrassing yourself and possibly giving her discomfort. Sometimes a chance is never a chance at all and you should not bother to try...