>A common beginner mistake I see on finance forums is when people calculate some notional hourly wage for their time, usually from their salary divided by working hours in a year, and then use that to justify any time saving purchase they want to make.

I see people talking about "what's your time worth" on hobby forums all the f-ing time. At this point I just assume they're justifying laziness because that's what it is far more often than not.

Interestingly enough, you pretty much never see people who are self employed and could be booking billable hours instead of doing other things invoking the "value of my time" argument for doing or not doing things.