This is the beginning of burnout.
Soon, you'll stop being able to think straight even into Monday. Other things in your life will fall to the wayside or disappear out of neglect. Monday will turn into Tuesday, Tuesday into Wednesday. You'll wonder why you even bother to show up.
Eventually, your employer will fire you for someone younger and cheaper, and you'll realize that you have no ability to maintain enough software development effort on your own to demonstrate to potential employers that you can do the work.
And even if you could, it's a sham, because you can't. You'll find that you end up being able to work ten, maybe twenty hours a week if you're having an especially good week. Your work won't be any worse, for quality, you just simply won't be able to force yourself to do it any more than that.
So, it's worth addressing that early.
I'm not sure why the mantra of HN is that "You just have weekend and side projects and stay up till 3 am while still making that 9am meeting and everything is great". Sure, that works for a while, until you hit your limits and your life falls apart. There's no road back from there.
Take it from me, you can truly excel, and nobody cares unless you can work 40, 50, or 60 hours a week. To PG's point from a while ago, "Nobody is willing to pay double for twice the work" - neither is anyone willing to pay half the rate for half the work.