It's far worse to never attempt something. If you never attempt something, you'll never know if you'd be successful.
1. Is it worse to fail at something or never attempt it in the first place?
Failing is not the worse thing that can happen .. In fact failing is a natural part of the learning process. We continuously attempt, fail, and learn throughout life.. From infancy to old age. One does not pop out of the womb and immediately know how to walk and talk and ride a bike .. Etc etc .. No, we first must learn as we go .. By trial and error, by failing our 1st attempts .. By growing as an individual.
Failing is just practicing for success. I failed at quitting smoking several times before I finally made it about 20 years ago. And that's just one of my failures that finally turned around. :)
Failures are stepping stones to success. How can one know his limits absent failure? It is much worse to never have tried than to have failed while actually trying.
They say people regret the things they didn't do more than the things they did. Hence, always give it a go no matter the outcome.
Depends on what you are after?