> a freelance developer who charges $100/hr spending 5 hours on Amazon trying to save a couple bucks on an iPhone cable. Cool, you saved $3. But you spent $500 to save it!
Only if you have more work lined up than time to do it. Otherwise it's just another part of your day, that was never going to earn money.
Seeking a client's still work though, nobody's working all the time. At least, if you're reducing sleep so that you can spend more waking hours on billable work, you should probably take a step back!
And I assume the starting point, 5h on $3, was an exaggeration. There's time for saving money, and there's money that's worth the time to save. My point really is that 5h doing non-work hobbies, spending time with family, or whatever, isn't a 'cost'. Not even necessarily an opportunity cost, since for that there had to be abundant supply, that doing it now doesn't mean you're not doing it next week, that there's always more already lined up 'for free'.
Only if you have more work lined up than time to do it. Otherwise it's just another part of your day, that was never going to earn money.