Yes its deadly.
Inadequate debt wont allow your business to grow and entrepreneurs will suffocate & die. (business will die)
High debt will drown you in the burden of interest. Yes more debt without adequate productive use will eat into your profit. Invest excess debt thoughtlessly and inability to repay will make your account NPA and your otherwise profitable business will also sink.
No bank /institutions will finance NPA accounts. Inability to raise finance means stagnation.
Debt is necessary for growth but its adequacy is what matters the most. Many businesses are out of business today just because of either of the two scenario mentioned above.
Understanding play of - cashflow , adequate sustainable leverage (debt) , criticality of margin & contribution , cash conversion cycle , inadequate working capital , debt trap , fixed and variable cost , current ratio , cashflow to debt ratio etc are very fundamental to every business.
Even if you do great business, illiteracy of financial implications will undo all your great marketing efforts.
All entrepreneurs deal with money & work for money but unfortunately many entrepreneurs do not understand money part of the business.