I know they are sponsored, but don't they carry their own keyboards to the tournament instead of opening a new one every time? O.o
Actually, professionals have almost as many keyboards as I do. Depending on the team, a fair number get broken due to ragequit. Mostly though, they get only a few months out of them at most before keycaps are trashed and keyswitches are worn out. Remember that whereas you might type a few thousand words a day, these guys? Are hitting the exact same set of keys for 4-8 hours a day, very rapid fire.
Also bear in mind that there aren't a lot of keyboards they're
allowed to use. The SteelSeries 6Gv2? Permissible because it has no macro keys and no added functionality. Anything with macro keys is automatically disallowed. Most of the serious competitions also don't permit bringing your own equipment. Usually they're using keyboards and mice provided by the sponsors, or by the team sponsors and pre-approved. (So for example, if the venue has no deal with SteelSeries? No 6Gv2 for you.) Most of the provided keyboards? Get thrown out or hosed down and sent along with the standardized competition rig.
Honestly, it's most likely that these keyboards are in fact, being sold as part of their sponsorship agreement with SteelSeries. Meaning they're brand new, either as spares for practice or provided by SteelSeries at massive discounts which they then pass on to fans.