I think answers might be skewed by life experiences/personality types/age.
I'm a SAHM after (willingly) giving up my career 2 years ago. We have a 6 bed house with no mortgage. DP has a job where he earns 100k+ a year working from home 9-5. We love it.
DP is nearly 50. He worked long and hard as a younger man to save for the family he knew he wanted one day.
I'm a decade younger. I grew up poor, moving house a lot due to rental contracts. My dad was absent for long periods and my mum's focus was on earning money and never me (yes, they were mutually exclusive). I worked long and hard to give myself more security as an adult and to ensure that I could financially support my parents as they aged. I never expected to find a partner and have children.
DP and I are both introverts. We don't go out lots because we don't want to. We enjoy the simple things in life - family time, walks, cycling, reading, gardening and conversation. None of these things particularly cost money so it has helped us save throughout our lives and allows us to be content with our lives as they are today. There isn't anything wrong with being an extrovert but I imagine it makes the isolation of being a SAHP harder to tolerate.
Mine and DP's ages mean that we had many of the experiences we wanted before we settled down together. If you're younger, I imagine that it's hard not to feel like you're missing out on something. The way we worked in our younger years has helped to give us the freedom to choose the life we live now, which in itself feels like an achievement.
The way I grew up also means that I really appreciate and cherish the time with my DC. I'm not saying others don't but my point is that I'm maybe more content with less stimulation beyond our family because the family stability and parent/child relationship is what I always craved when growing up. I always knew I'd rather have no money but family connections if I had to choose between the two.
As I said, I love conversation about topical issues and I still get that stimulation from my friends. This is part of what stops my brain turning to mush as is the extensive reading I do. However, this is part of who I fundamentally am. I was the same person before I had DC. The same goes for DP, so the lifestyle we have suits us. I totally understand that it doesn't work for everyone. I'm glad that we're fortunate enough to have the choice of doing what works for us.