I assume that you are referring to keyword stuffing : YouTube keyword stuffing is a process of stuffing keywords in the description field in the hopes of getting ranked higher in search results. YouTube often decides to terminate accounts that are using keyword stuffing.
How do people do it ? They just do it, because they churn & burn YouTube accounts, without need to bother if any of these YouTube channels get terminated after sometime. Why do they do it ? The short duration that the video or channel is alive, is good enough for them to achieve their objective, which could for example be to drive massive traffic to some website, etc, etc, etc.
So, there is no way to keep doing it on 1 particular YouTube channel and not get penalized. However, this technique is used as explained above.