I work for a charity that generally, on a day to day, we see the worst. We offer free, unpaid, voluntary work, and are 9/10 thanked with abuse, rudeness, ridicule, and disdain. These are people who have few options- it's us or nothing and they choose us, but unwillingly and arguably without true "choice". When our help yields good results, we get told we were no help and they could have done it without us. When our help cannot help, we are told it's our fault.
Imo people are kind. Because we all still help because we believe in justice and understand that our clients are victims in many ways.
The one in ten that show gratitude make us feel good, but they aren't common. And often make us feel worse- they shouldn't need us, they needn't be grateful and a decent society wouldn't have put them in a position that leaves them reliant upon us.
So too, when we do fundraisers- standing outside supermarkets with tins for instance- people are generous. They are kind and give what they can, and when they can't they (unnecessarily) apologise. Men dig through their pockets and give whatever they have, women search their handbags, many- a shocking amount!- go back to their car and come back having found change to put 20p or whatever in the tin. These people don't see the outcome of their kind donations, they don't know who they help, and often have no idea what charity they even donated to- they just see a tin and offer what they can. There's no gain for them. They were just kind. Because people are.