No one has ever said that if you follow Whitehat SEO that you would be guaranteed good rankings not even Google said that. But using Whitehat SEO practices guarantee you that you won't be banned from Google's index or penalized or filtered.
Black-hat SEO is a short-term strategy. It guarantees that if you are caught your URLs or domain will be filtered, penalized, and in extreme cases banned from Google's search.
A simple saying "Don't put all your eggs in one basket" i.e. being totally dependent on Google traffic. So, if your business is totally dependent on Google better avoid Black-hat SEO. It's Google's index and if you want to use it better learn to play by their rules.
If someone can add some additional color, it will be helpful for many.