[Symmetry]

In the 90s there were dozens of leading edge fabs. But while the barriers were high back then the capital investment needed to get into the next node has gone up exponentially, about 15% each node, since then doubling every 5 years. It took less than $1 billion to get in the game back then but over $20 billion now.

[segfaultbuserr]

Rock's law, the inverse of Moore's Law.

https://en.wikipedia.org/wiki/Moore%27s_second_law

[qeternity]

It's not clear whether this is cause or effect. The insatiable demand for silicon fabbing has arguably made a $20B plant today more economical than a $1B plant 25 years ago.