That's only partially true. For instance, if I knew I was going to live to 120, it'd be much easier to decide whether to have kids (20 yr opportunity cost), do

That's only partially true. For instance, if I knew I was going to live to 120, it'd be much easier to decide whether to have kids (20 yr opportunity cost), do a PhD (4-7 yr opportunity cost), etc. Currently, you can have about 2-3 careers if you want them, but if you lived for 120 years, you could have 4-5. Basically, it makes commitment less costly in a very real way that makes several choices fall below various "go" thresholds.