Why is it when you have so many plans or goals, that people look at you as if you can't do it ? ?

It's like being prejudged or passed judged they just assume you can't. I tell my friend a lot of things I'm going to do, and he always look at me and then goes "Can you really, if so how?", and then I'm ready to explain, but he doesn't wanna hear the plan so I question if I'm thinking to far ahead or is he thinking to little. On this not he's stuck in a weed cycle which don't get me wrong that's his choice, but I often know once I have the freedom I truly want I wont care for weed hell maybe even alcohol, and i asked if I were to disappear for 3 years to train (which I will) what would he do ?  I tried not sound like I would ditch him ( I would (ik terrible), but i've been wanting this). The point here is every time I mention crazy ideas of mine people always give me a second look like "no way in hell, your just going to do the same thing", but there the one's stuck in a cycle not even thinking or considering ahead besides the wants and temptations of today society maybe I'm thinking to far ahead. Although I refuse to believe so because the mindset is the first step of I can, and will do as I please