A discussion on debt in Victoria 3, in comparison to debt in Europa Universalis 4. Debt isn't always a bad. It can actually be a very GOOD.
Your country's debt is paid to the owners of the buildings, generally the capitalists and aristocrats. Paying interest in debt increase these pops wages, which increases their standard of living. Higher SOL causes them to increase demand for higher end commodities, and importantly higher demand for services. Higher services consumption can increase the value of running a consumption tax on services. Or wine, or luxury furniture and clothing.