I feel like "programmers are not computer technicians" joke is kinda overused lately. It doesn' matter if we are not technicians, we are very knowledgeable in computers and people knows that. People of course will try to get help from you when they can so it's not a wonder that they ask you to help with something they are not confident. Everyone that exercises practical professions lives through that. If your sister-in-law is a mathematician it's normal to ask for help if you are not able to come up with the right algorithm for the task. People depend on each other. That's how we survive.
But I'm not saying start helping everybody that can't open a pdf file. Just know who to choose to help. If they are a capable person or someone that's a part of your everyday life they will most likely repay you when you are also in need. Believe me everyone needs help time to time.