they design and produce chips, TSMC produces but does not design, NVIDIA and AMD design but do not produce
That's the point. They have more employees than the #1 silicon fabricator, the number #1 GPU designer, and the #2 CPU and GPU designer, COMBINED.
all these companies combined design and produce more chips than intel combined
Number of employees is not the correct comparison, total labor cost is. Intel intentionally pays middling compensation so you would expect to need more people to do the same job.