You are mistaken.
100,000 of the best out of a pool of approximately 10 million professional software engineers worldwide is a sizeable portion. Additionally, not all 10 million are even close to being up to BigCorps peculiar standards (perhaps the standard is "someone competent enough that they could potentially build a competing product line").
Goog, Meta, Amazon, Apple, Oracle.. all have huge rosters and it adds up to a significant portion of the market. There is also a huge amount of medium sized whales such as SAP and PayPal who in total end up also consuming a lot of the talent.
