I think the answers vary a lot, but I'll give you my own background.

My parents both started their own businesses. My dad's company focused on computer modeling software geared toward supply chain management. His company was amicably aquired recently and he chose to continue to work at the aquiring company in a very senior position, but he certainly doesn't need to work and I think he might retire soon. Even though my dad is doing great, I think my mom is living the dream. I don't think she's ever going to retire. She is happy and fulfilled by her job (she runs her own business in healthcare) and she's thriving economically. We don't really talk about money much, but if I had to guess, I'd say their net-worth is for sure in the multi-millions.