<human>: Can you condense the text into three sentences or less?

Was going to post this from a throwaway, but whatever. 

I work for a small newspaper that has about 12 total employees. So today the office manager went around collecting money ($5-$10) from every employee to purchase the owner a gift. I declined, and was informed that even the new girl (who has been there for only a few days), who hasn't met the owner, pitched in some money. I said nothing and just went back to work. 

Later on in the day a few people made a couple of snide remarks about how 'cheap' I am. I asked a coworker if she thought it was rude of me to not have contributed, she informed me that it was. She said that he provided a nice working environment for us (he does) and that he and his wife (another owner) are good to us. I calmly explained that treating your employees well usually means you have efficient, happy, employees, and that our relationship was based off of an agreement: I show up to work, do the best job I can, and he pays me in return. I neither received nor expected anything on my birthday, and didn't feel in the least bit slighted by it. 

I don't mind contributing, either - so long as there's a purpose. One of the girls that works in the front-office had a run-in with a stray dog and was out of work for a few days. I chipped in $20 ($10 more than everyone else) to help her offset the money she was going to lose by not coming in to work.

I just don't understand. Not only do I think my employer isn't going to care that we all got him an expensive $100+ gift, but I'm not clear on why I owe him anything, or why people are so upset.

Did I miss something fundamental about being human?
<bot>: Wealthy employer's birthday, everyone in the office pitches in to buy him a gift. I said no. My coworkers are now pissed off at me.