https://libn.com/2018/11/14/usps-reports-loss-for-12th-straight-year/
"USPS reports loss for 12th straight year"
And its billions of dollars
And it's not funded by the federal government. "The Postal Service is a government agency, but it operates as an independent business without direct taxpayer support."
Here's a major reason why there are losses:
"The Postal Service said it had made "significant cost reductions in areas within its control" by 2011 but claimed it needed Congress to approve several other measures to boost its financial outlook.
Those measures include eliminating mandated retiree health benefit pre-payments; forcing the federal government to return Civil Service Retirement System and Federal Employee Retirement System overpayments to the Postal Service and allowing the Postal Service to determine the frequency of mail delivery."
If they weren't forced to pay benefits in a way no other business does, it's likely there would be no losses.
I'm amazed the USPS is as strong as it is and thought it would on its last legs by now.
However, you don't address the reason it's still strong. It's not because of old people. It's because businesses make untold billions from using USPS for advertising. When that stops being profitable and letters cost $2-3 to send, it will cease to be the way it is.