Unrealistic Targets - Are They A Good Idea?

I tend to have two sets of targets in training and general life, one that I have as my I will do that, and one where I would like to do it.
The former is generally hard work but sensibly achievable, the latter is often unrealistic and usually out of reach.
As someone who hates failing in general why would I do that to myself? What is the benefit?

Well I have achieved many of my unrealistic goals in the past and can look back at what seemed unrealistic years ago and realise that I am doing those things easily now.
It was unrealistic to expect myself to be able to bench press 60kg once upon a time, my current unrealistic goal is 100kg, and I am probably able to do 90 or close to at the moment for 1RM.
It was unrealistic to expect someone to take me seriously enough to invest feelings and effort to convert the a hole I was into a decent husband and father but I did it and we are a solid happy family. This was so unrealistic I never even set it as a target.

Many of the things I have set as targets have had a time frame and that has usually been where I have failed. This year’s training targets are powerlifting stats of 200/100/210 and regular running pace of 8mph over the 5.25 mile route I am using. On their own neither of these are too ridiculous as I am close enough to them to be able to get them within the year, but to increase power and stamina at the same time is not easy and there is a strong likelihood that success in one will result in failure in the other. I want to be wrong as I have been in the past, and truth is managing one fully and getting closer to the other will feel like success but I like to aim high.
There are a few unrealistic targets I have outside of this which are less unrealistic but may involve a certain amount of luck.

I do remember setting targets that weren't time sensitive and achieving them in the past, the feeling when you get there is awesome. One that I remember was being good enough to be in a formal dance performance. I danced for many years, ballet and contemporary and I progressed from an uncoordinated mess to a reasonable standard, but only the blind would fail to see the difference between me and a professional dancer. However back in 2000 I did it and loved it.

I think unrealistic targets are a good idea and will always have them, but I keep the achievable in mind too. Achieving minimum is time for a smile, the unrealistic is Archimedes time, though running down the street naked is not compulsory.
There is however a danger. Pushing yourself this hard all of the time causes regular injuries even if they are minor and does make you hard to be around. The important thing is to remember you are the obsessive freak and everyone else is normal, so doesn't care.