I suppose it depends what the context of "pick up the slack" means but, in general, I'd find it perfectly normal for a co-worker to take off at 5pm for an evening activity, family-related or otherwise.
I do tons of work-related travel and the like. I also don't do nights and weekends work day-to-day. Work emergencies happen (as do odd-hour conference calls) but it's rare I'll schedule evening activities around work when I'm not traveling.
Company A will pay me $400k/yr, but only if I make work my top priority
Company B will pay me $150k/yr, no matter what
Please explain why it's "naive" to choose Company A. I don't need "ownership" in the company to profit from this.
I don't see how the company's reaction to my death factors into the decision at all.
But that's not even close to the situation most developers are in. Most are getting paid somewhere around an average salary, maybe with a few probably-worthless stock options, and they're getting asked to sacrifice their personal time working for free to make founders rich. Working extra hard isn't likely to advance their career at all; it just gives them a reputation as somebody who is willing to take abuse.
If you're in a situation to make a crazy good salary by working hard, by all means, do that if you want. But understand that situation is very rare. And even if you're getting that deal, the person sitting next to you might not be in the same boat.
Working hard to make other people rich is a sucker's bet, akin to playing a slot machine. For a rare few, it pays off big. For a somewhat larger cohort, there's a modest payoff. For the large majority, it's just wasting their career and their time.
Second, if you want to dedicate 10 years of your life to work, make money and retire early - it's a reasonable choice for many. But if it goes into 40s - why do you need money, if you would not be able to enjoy it constantly working? Your money may go straight to doctors and psychotherapists eventually.
I suspect you'd find it quite ridiculous to have to pick up my slack as I have to run at 5pm to practice with my bandmates, at least if you weren't paid correspondingly more for the extra effort. Change that to a PTA meeting or soccer practice, though, and suddenly it's how dare you suggest that I get paid less for not only doing less work than you, but doing some of the work I was expected to in the first place!