What's the benefit/point of paying for a day pass?

This Sky Club has a number of amenities including showers, food and beverage services (well liquor is free of charge).

Been there before when there was a storm and hundreds of cancelled flights. People were lining up to get a day pass and Delta eventually stopped issuing them for the day. Food and drinks included for your entire stay can easily pay for itself depending on your situation.

Being able to stay in the club for a day. This may be officially valuable if you need quiet for a conference call, or you have a long layover so you can avoid paying for outside food, or you need a shower and there is one for free in the club, or you need better Internet access than is in other parts of the airport, or you are traveling with a club member and you want to go in together.

if you're lay over is long it's vosr effective

The people are very nice

It all depends how long you are going to stay. How much you drink. How much you eat. Do you need a quiet place to work? A day pass costs me $29. One beer in the airport typically costs $10. Sime math.