So, the business proverbs they live by both give them hope and amplify their anxiety that their opportunity is slipping away with each day that they're not hustling.
Speaking as someone who just does what he enjoys doing and ended up with a marginally successful business as a result, I have to say that I genuinely don't get this mindset.
Then again I don't "hustle" either. I (and my employees) just write code that solves problems and creates value for bigger businesses and they pay me good money for it.
I find this phrase trite and full of significance at the same time.
Much of existentialism is an investigation of anguish — the permanent, low-lying anxiety of existing and trying to find meaning in life. This anxiety comes from, and is the process of, realizing one's potential.
Thus, anyone who realizes that their current station in life is not the top of their potential is bound to not be happy with where they're at.
This is not just in business and money. You can be anxious about not having enough fulfilling friendships or spending meaningful time with your children, or any other thing you value highly. Many people give up on stressful business enterprises, but move their anxiety towards other targets — family life, politics, future events, or specific interests.
Conversely, only those who do not realize the gap between their potential and their current situation will be satisfied. The more qualified and diligent you are, the more likely you are to be aware that you're not your best yet.
It takes active work ("hustle" of sorts) to be diligent and unworrying: meditation, therapy, etc.
Gary Vee is a successful businessman. He built upon an existing business and made it more successful, that's a great accomplishment. I wish I had 10% of his success. But he's not a guru, he is nowhere near elite. Plenty of people have done more impressive things than him but the memes around him being some sort of guru on being an entrepreneur are far more outsized than his actual success. But the way his followers treat him is completely disproportional to what his actual successes are.