I'm not throwing it around or twisting it awkwardly (the cord is fine, it's the end piece that's beginning to break off), and I haven't really taken it traveling anywhere. The only reason I can see it breaking is the very few times I've accidentally dropped my phone while it's charging.
How do I stop this?

There's wireless charging the galaxy phones but they already have it integrated but you can do it on any phone
https://youtu.be/vnNG7WWvojc
Here's a guy who does it, it's simple.
Also don't buy 3rd party cords, and if you do get them from big brand like Belkin.

I don't know how you guys break your chargers, I had the same one for about 4 years now

Put the spring from a pen around the end that you put in your phone. It will help with fraying