Not knowing why this is critical, and massively positive, is a lack of imagination.

A balanced budget means minimization of your debt service. Cities can invest, they can also take on debt in various forms. There is "good" debt which services itself, but bad debt can be very expensive.

Balancing the budget means more cash flow to pay down existing debt quicker and not have to create new debt. It also means making new investments.

Maybe in 2 or 3 years you can build that orphanage, and you can do it with money your investments have earned, instead of raising taxes or taking on new long-term debt.

This could make NYC more self-sufficient and prosperous in the long run, and less reliant on outside creditors, which limits the leverage of outside parties against the city.