There is lots of truth to this, but it's not that hard to save up for 6 to 24 months of expenses on an engineer's salary, assuming you are living within your means. Dependents complicate the situation, but don't make it impossible.
I can't risk my savings on a startup, because running out of savings means homelessness and hunger. Even without dependents, many people don't have parents willing or in a position to be the guarantor of such an investment.
You now have a gap of unemployment. How does your next employer see that? I know a common tactic in IT is that you're a "consultant" when unemployed. Hiring managers see through that readily.
So what then? You have a failed business, unemployed, and take a pay cut on your next job... all for the hopes that you might, just might strike it rich?
Again, this situation doesn't apply for those with well monied family and significant connections.