I don't feel like I'm missing out, but I do often lament the lack of time[1]. It is an interesting observation though of feeling on the outside of an amazing time. Do you feel like you are not able to 'join' the party? And if so what is holding you back? [1] Spending it reading HN not withstanding :-)
I run a small consulting company doing primarily hardware and embedded software. I've got a lab set up in my basement with almost all of the gear that I need to do that successfully (spectrum analyzer, oscilloscope, and logic analyzer being the big 3 that I use pretty often). I do well enough at it that I don't really worry about money; I won't be retiring at 35, but I'm doing well enough that I don't think much about my chequing account balance.
There's the occasional crunch time, but for the most part I work hard for clients a few hours a day and spend the rest of the day learning & experimenting[1], reading, taking the dogs for a walk, doing yard work, etc. When I'm working on the software part of the work, we've got a family cabin a few hours away that has excellent 4G coverage. My partner and I will pack up the dogs and head down there for a few days in the middle of the week if it looks like it's going to be nice weather. She too has a job where working remote is often an option, so we'll get up, make some bacon & eggs with pancakes, take the dogs for a walk around "town", and then come back and do a few hours of work from maybe 11-3.
When I was working full-time+ in startup land, I definitely felt time poor. Sure, I sometimes miss being at the party, but I feel way less stressed now and happier with my life.
[1] The learning & experimenting often involves noodling with a new piece of software or hardware. It's often still screen time, but it's at my own pace and on my own terms. And over and over, it's turned out to be relevant to potential consulting gigs with a 1-3 month turnaround. Learn some new piece of tech, talk about it to friends, and tada! there's someone who's willing to pay me to use whatever weird niche thing I picked up to solve a problem for them.