Why do pro gamers use such a low DPI?

One thing is accuracy, another is consistency. It's been said and written that if you set your mouse DPI too high, some sensor will eventually start skipping pixels and such. read more

Pro gamers use low dpi for precise aim. In my opinion this is preference. This kind of method is mostly known from a game called csgo. That game is heavily influenced on mechanics. Pros need to use low sensitivity for better weapon spray control and steady aim. But they have sacrifice quick flicks/fast turns. read more

In practice, a DPI above a few hundred is totally unnecessary and may actually lead to all kinds of other problems and inconsistencies with the mouse. That's why you should not set your DPI to ridiculous values like 6000 or whatever the newest flashy gaming mouse can do. read more