“If you knew that you wouldn't get a lecturing position after the PhD, would you still do it?”
Putting it like that, the answer would be no. But I like to take things as they come. Many things can happen in three years – different opportunities can arise, you can’t predict what will happen to your health, your family, etc. I like to take each day as it comes and not speculate too far like that. But yes, I dream of an academic job and I haven’t even started my second PhD yet, hee hee (qv. the thread “I was forced to quit my PhD by both my supervisors”).
My dad recently told me “stay in that field. This field is going to be taking off in the future. Then you can sit in a nice comfy chair in your own office and fart, just like I do”. (He is 70 now and is still working… he took the industry route).