Why are people so judgemental its incredibly sad..

I just went to the Dollar store to pick up three pregnancy test and I was standing in line sweating due to me coming back from work. This young guy who was at the cash register was trying to pay for his school supplies but,the women told him loudly that his card was declined i was angry she shouldve said it quitely and he was putting his school supplies away while everyone was looking. My gut was telling me to pay for this young teenager and I quickly told him I'll pay and he thank me Soo much I was proud of my good deed I would want someone to do that to me one day if I need it. I put my pregnancy test on the side and finish paying and went back in line. These 3 teenagers was Basically making fun of me and was talking about me saying why am I buying those test, I look so young (am 21) ect.also talked badly about me paying for the young man I tried my best to ignore them because I dont need to snoop in there level. Pretty sad how young people don't know how to be kind to others.