I don't get it. Are you saying that tech debt causes entire companies to fold?

It creates and exacerbates more obvious symptoms, yes. Companies that couldn't transition to the PC era. Likewise for the internet, mobile, etc.

Some companies don't go under, they just buy another tech stack. Depending on the circumstance, that's acknowledging the risks of technical debt.

Some companies make that purchase, fail to reconcile new tech with old (also tech debt) and waste piles of money