Because the harder you try to pull them up, the more they are subconsciously trying to pull you down. Some of this will be intentional; most of it won’t be.
But that unintentional programming is the most deadly. That’s not to say that your family and friends don’t mean well; I’m sure that, in their own way, most of them do. Parents teach their kids to go for the secure jobs, maybe even get union wages if they’re lucky. Teachers and guidance counselors tell you to “be realistic.” Friends tell you not to strive for too much, lest you be disappointed."
But deep inside your heart you know that you can be greater, you know that if you step out and take that risk, you can change everything.
Don't let the "good intentions" of others be a hindrance to what you can achieve. Don't kill your dreams because of someone else's nightmares...