That's only natural and should be expected. It's just wear and tear, it degrades over time. Charging your battery while you're actually using the computer kills the battery twice as fast. When you have a battery, the laptop takes energy from the battery, even if you have it plugged in. So when you have a charger plugged in, the battery is being forced to do twice as much as it should since it needs to charge up and then give out energy to the laptop all at the same time. This goes for any device. It's best to use it then charge it when the device isn't in use. But batteries will die out eventually, just some have a longer life expectancy than others, but it all depends on the individual use of the battery.
I didn't know this a while ago and now my battery is dead, but I don't feel like buying a new one so I just keep my battery and charger in at the same time. xD YOLO!
@OP, I like MSI and Lenovo laptops just because they're generally strong and durable. I'm thinking of getting a new laptop but mine still works so I don't care so much about a new one at the moment.