Why is my MacBook Air's system data so large?

I have 245.11 GB of Storage capacity on my MacBook Air; My system data is taking up a WHOPPING 123.53 GB, which is OVER HALF of the capacity. OVER HALF of my computer storage is completely unaccessible and has ZERO information provided by apple. I guess apple just expects users to be perfectly fine with an entire half of their device banished to the unknown depths. This situation is ABSOLUTELY unacceptable, and if step by step instructions to remove most, if not ALL of my "system data" can't be provided, then please direct me to a sales representative who can assist me with a refund, trade in, or credit.

[Re-Titled by Moderator]