One of the things that's worth keeping in mind when one sees people without money seeming to spend that money on luxuries is that it isn't always necessarily what it appears to be. For example, I'm poor, but I have a relative who sometimes takes me along to sporting events -- I don't pay for that ticket, I couldn't sell that ticket if I wanted to (i.e. it's not mine to sell, he'd take someone else if I didn't go)-- but if someone saw me at a game and didn't know better, he might think I'm blowing money I don't have, even though the cost is $0 to me.
It's also worth noting that when people are down and out over the long-haul -- sometimes due to health issues, sometimes due to a really bad job market, sometimes due to being old and having no real skills, sometimes due to whatever, lots of scenarios -- that they are sometimes going to want to have a beer or some small luxury just to try to keep potential severe depression over their situation at bay if they can find a way to swing it.
I don't think people who generally have it good always realize that people who are in bad situations long-term sometimes need to live for the small things. They don't understand what it's like to be down to the last dollar in your pocket constantly and not have much hope of digging out of that. Every day is a struggle financially, sometimes just to have food on the table (Sometimes low-quality food like ramen that can cause health issues), and you tend to lose prospects of ever being able to get married and start a family, live in a house in a decent area, etc.. You're often stuck in a ghetto somewhere by yourself or with roommates you don't care for just growing older day to day, with the things people generally derive meaning or a peaceful feeling from not there and the constant drone of the city around you and a not-great general environment (Try to get a landlord in a slum to fix basic maintenance stuff in a timely manner, for example). Sometimes that party you might see that guy going to might be what he does to give himself something to live for day to day or week to week, in a way (I personally don't generally like parties, I'm just going with your example).
If you're in a bad situation and can dig yourself out -- you might go totally without everything for a while. If you're going to be in the rest of your life, though, yeah, every once in a while, if you can manage to after you pay for the rent and the groceries and such, you might try to obtain a small luxury. Otherwise, your miserable life is going to get unbearable over the long haul.
And, no, I really don't think big corporations should be able to charge higher fees to people in dire straights. Just set a price for everyone that will make a small profit overall and offer that without conditions. It's the right thing to do. We give these corporations all sorts of special rights and limited liability under the law -- in exchange for that, we should make sure they treat everyone equally and work for the public good in at least a limited way IMO. It's the least they can do.