For most of my life I have assumed that people are mostly good, and while this may actually be true, when I reflect on some of the times in my life I was stressed out it was due to extending myself to others, to then later feel taken advantage of or on the hook for future favors.
As an example, I helped an older neighbor put up a wireless security camera. I had the same camera and I used a double-sided industrial strength adhesive to affix it to the side of my house. When my neighbor asked for help and I made it clear upfront that I'm not too handy, and this is just what worked for me. I didn't have a drill or screws for a proper install and in my case those weren't needed. Mine had been installed for 6 months at the time using the adhesive. I told her that if she was OK with that then I'm happy to get out the ladder and install it. Turns out, the siding material on her house was different than mine and her camera only stuck to it for a couple of hours before dropping off, swinging by its solar-panel's charging cable. She stormed over, knocked aggressively on my door during my dinner, and marched me over to the swinging camera to show it to me suspended in the breeze. Her girlfriend also commented on my inept handy work.
So, I helped a neighbor and was honest upfront with a disclaimer. She accepted and then when things didn't work out she made it my fault. I was the schmuck. Oh, and I setup the software on her computer and phone so she could get email alerts for motion activity. Despite the generosity I showed with my time, when the outcome wasn't ideal I got blow-back for my good deed.
This also reminds me of the time I let my choosing beggar neighbor hop on our WiFi network until he got his installed. Needless to say, he never did get his own and became indignant when I cut his access off after several months of free use. Yep, lots of people suck.