No. It doesn't have to be a bubble at all. It just has to be a cycle of rapid capital equipment build-out that returns to more normal levels in a few years.

Hard to believe that an industry making money hand over fist are reluctant to spend tens of billions expanding capacity that won't come online for years?

There have been SEVERAL crashes that have wiped out the market and it's the reason there are so few players, the rest of them went bankrupt after periods of over-expansion. (in the 80s caused by Japan, in 1997, in 2001ish after the dotcom bust)

You're even calling it a bubble so it's not exactly "hard to believe" it will pop.