Why do y'all do it?

I want to preface that I have nothing but the utmost respect for the USPS and its workers. I applied for RCA when I was working a customer support call center, was offered a job, but it was 2 days a week, depending on their need. With no reliable schedule I couldn't work it around my first job. Despite being promoted out of the call center working for USPS has still remained on my mind. It feels like it serves a moral good and I could feel proud of the work I'd do. But feeling good only gets you so far.

What gets you past the:

• Weak union
• Bad management
• Post-2012 contact pay/generally being underpaid
• Low quality overpriced uniforms
• Uniform allowance that doesn't even cover the uniform
• DeJoy
• Amazon
• Excessive overtime
• Poor quality LLVs
• Asshole customers
• Earbud restrictions

and how did you overcome the challenges of being part-time as a CCA/RCA before being able to convert to full-time career? Is there just that much overtime available for CCA/RCA that its basically full-time hours anyway? I'm in NH and cost of living doesn't square with being part-time for 2 years.