There are some traps and stigma with big, sweeping ideas.
Some real problems too.
Mostly, they look simple and reality is not simple. But then again sometimes reality is very simple too.
Anyway, I think the realistic failures and threats shouldn't stop anyone from dreaming unrealistically big.
An unrealistic goal can still be productive. Some changes are not incremental and if they were, they would be so small to be demotivating. We can't have that.
Dream big!