Unless you get enjoyment on some level from the financial security of having a bunch of money saved (i.e. you sleep better at night because of it). It's like purchasing insurance - if you never end up using the insurance, that doesn't imply you made a poor decision (wasted money) in purchasing it.

Likewise, knowing that an expensive medical emergency could come up means that having considerable savings is an appropriate response.

Or you could take the opposite view and arrive at the same conclusion - if you have a healthy lifestyle and expect to remain healthy, you might predict that you'll have a long lifespan, making it prudent to conserve your retirement savings by spending it at a very slow rate.