Why do people sacrifice material just to give a disadvantage to another in 4p?

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Avatar of Trexler3241

(please move this thread if it isn't in the right place)

In 4 player chess, I experience people just sacrificing their material just to give a disadvantage to me. This has been happening quite a lot. I'm pretty sure people that are doing this just are beginners, but this also happens at >1300 ratings. 

What's going on here?

(sorry. I will have to post a game on Friday)