During the last month, I applied for PhD programs in some of the top US Universities in my scientific field. At the same time, I applied also for a PhD position in a very good European University. About one month after I submitted my application to this European University, I was offered a full-time, funded PhD position, in which I was supposed to begin as soon as possible.
Admissions for the US Universities are announced in the spring. So, I currently have an offer from Europe and a very short deadline for accepting or rejecting this offer. My ultimate career goal, however, is to study and work in the US, and there are some serious reasons for this. If I reject this offer from Europe and if I won't be admitted in the US, I will have lost every chance for a PhD, since a long educational gap will have been accumulated, putting my career at risk.
So, I'm thinking to accept this offer from Europe, until next academic year, and if I have a positive answer from the US, then quit my PhD studies in Europe and begin a new PhD in the US. I would like some insight about people in Academia. I acknowledge that such a scenario might affect the whole PhD project because of my possible withdrawal. Would this considered to be immoral? Could I have any consequences? Could this choice of mine - quit a PhD for another one, in a new country - seem bad to prospective supervisors in the US?
I already know that pursuing a PhD is a serious career choice, and I have no intention to take silly decisions for no reason. I just want the best for my career. To my eyes, this would be no different from quitting a job for a better one, for a better "company", in a "market" with greater opportunities. I would appreciate every advice from you people, since I have no experience related to Academia other than my undergraduate studies.