It's not. Every instant of your life you're making choices that lock you out of opportunities. To claim that you're able to measure the opportunity cost of your

It's not. Every instant of your life you're making choices that lock you out of opportunities. To claim that you're able to measure the opportunity cost of your current path is to claim that you're able to know the path that would have led to the greatest reward and measure that reward. At best you could say that in hindsight a previous choice you made was suboptimal.