Interesting post/discussion, and very relevant to my life--last year, at age 49, I did a life-inventory, realized I had enough savings to last me well into my 80's, & so pulled the trigger & retired. It was def. a much easier decision for me than most people my age as I'm not married (no one else to consult) & I don't have kids, so I don't have that added financial stress. That said, I also won't have anyone to rely on for help / assistance when I'm old, so there is that to consider, too.
OP mentioned taking 10-15 years off and then trying to return to his current career; imo that's extremely unrealistic. First because OP is in a highly technical field, and it's unlikely that he's going to have the desire / discipline to stay current during his prolonged "sabatical". Secondly who can predict what industry disrupters will occur over the next decade? Third and perhaps most important, OP isn't taking into account ageism, which is a very real thing. Few employers, when faced with hiring a 35 year old versus a 60-65 year old who's been out of the industry for the last decade, are going to choose the old geezer. And just because at 60 or 65 years old you may not "feel" or self-identify as "old", make no mistake--to anyone under 40 you are old as ****.
So yea, if you don't have the nest egg needed to retire permanently now, the more realistic option is to continue to work part-time, or realize that at age 60 or whatever, you'll likely end up working at a position far below where you are now, if not in an entirely different industry, i.e., "Welcome to Walmart!"
That said, clearly retiring at 50 is a helluva alot better than retiring at 65 or 70. I just got back from a 6 week trip to Peru, where I saw all these retirees trying to walk around various ruins and physically just being unable to do it. Being able to retire early is great in terms of being physically able to really enjoy the world (if travel is your thing) but you also feel like somewhat of an outlier, as most other travelers you meet are typically under 30 or over 60 years old.