This isn't true. It used to be, as a new fab would appreciably add quantity. At 1M wspm in 2015, a new 100k fab at the most modern node would add effectively 20-30% capacity, and usually multiple.players at once, since all had cash.

Now, the relative shrink is tiny, so capacity adds are just wspm, in effect, and that gives 5%.

Put differently, you cannot invest your way out of the shortage, or into meaningful share....so you take profit.

apparently wspm is Wafer Starts Per Month

guess I'm interpretting "1million wspm; add 10%; was effectively a 20-30% capacity increase" in 2015.

Not sure where 5% then comes from. Guessing "relative shrink" is referring to process size (5, 4, 2 nm, whatever) not linearly corresponding to density of transistors, etc.