It only takes 15 mins under a baking sun without sunscreen to begin feeling regretful. The pain often lasts up to week after the burn, and the long term effects of repeated exposure add up over time.
The value of sunblock, on the other hand, is not only felt in the moment and the week after, but over a lifetime of consistent use.
The inconvenience of prevention is often an easy price to pay when we take the long view.