It's very delicate because from personal experience most projects are likely to fail, and most projects start way over ambitious (almost a natural bias). What takes lots of experience to learn is also that that's not necessarily a problem. It's ok to fail sometimes, and it's ok to be overambitious at the beginning and scale back to achievability, most of the time.
Initial ambitions largely set an upper bound on whole project possibilities -- you generally want upper bounds set pretty high. All projects have unknown unknowns that will reveal themselves, and modeling this kind of meta-knowledge is difficult and perhaps not worth the effort.
So to offer a general counterpoint, it may be a valuable skill to listen to constructive advice including ones poking holes in your ideas. The key is to persevere in the face of problems, as long as they're not obviously intransposable (tip: don't go against laws of physics, e.g. thermodynamics or newton's laws). If those hurdles would come up sometime, it might be better to devote more time early on to overcome them.
Initial ambitions largely set an upper bound on whole project possibilities -- you generally want upper bounds set pretty high. All projects have unknown unknowns that will reveal themselves, and modeling this kind of meta-knowledge is difficult and perhaps not worth the effort.
So to offer a general counterpoint, it may be a valuable skill to listen to constructive advice including ones poking holes in your ideas. The key is to persevere in the face of problems, as long as they're not obviously intransposable (tip: don't go against laws of physics, e.g. thermodynamics or newton's laws). If those hurdles would come up sometime, it might be better to devote more time early on to overcome them.