Do you mind being more specific? Are you dissatisfied with the amount of money your first degree would allow you to earn, or do you think the type of job you're qualified to get will be unsatisfying/boring, etc? If you based your degree on something you like, and others encouraged you, why do you consider it a rash decision? Why will the second degree be better?
I do think that studying Physics (which is one of my greatest passions) will not bring me the financial situation that I would dream of. Neither do I think that, despite liking the subject a lot, the job that I could get with it would suit my taste. What I am ultimately searching for is a balance between earnings and enjoyment of what I am doing and my point is that I highly doubt that this degree will bring me such a balance.
I say it was a rash decision because I was not convinced of this till the end, but nor was I convinced that I wanted to do something else. So even after all the thinking, I was not 100% sure that I wanted to this. I still think that it is way too early to decide what your future career is going to be at 18 years old, that's why I don't have many regrets for choosing this, as I have had the opportunity to think about what my future aims are.
In addition, I was greatly disappointed with the quality of teaching - not at my university only, but generally in this country. I feel not challenged enough - certainly not at my level of intelligence.
As for the second degree, I am actually weighing the pros and cons of more choices and I will wait another year before going for it. This time I really want to make sure that I take into account the future as well and decide whether I want to stay in this country or not.
(sorry if my phrases are a bit odd, since it is 4AM here and I really need to sleep)