Why can a Large and Long term National Debt?

-If it gets too big, then Firms and Nations may stop Lending to the Government, restricting Growth -Future Taxpayers will have Large Interest Payments on Debt to pay. This is an Opportunity Cost as Future Governments may have to use Austerity thus Little Economic Growth -Inflation and % Rates rising from Excessive Borrowing. Public Sector may also be Gigantic, 'crowding out' Private Sector Spending. [Although if the Economy is Boosted, the Private Sector may Catch up - Firms will Invest more] -Large Debts aren't Attractive for FDI as there is Uncertainty