That hype cycle doesn't apply to Nostr for the same reason it didn't apply to the Linux kernel. Both are developed by a community of programmers, so there's nothing to sell or invest in. Rather, all the money to be made is in using Linux/Nostr. And many companies pay programmers to write code for Linux, because those companies make lots of money using Linux.

However, Nostr is such a simple protocol that I doubt we will see companies paying for Nostr to be worked on in the same way as they do with Linux. Afterall, Linux is an implementation, whereas Nostr is a specification. So, if any company is going to pay Nostr developers, it's going to be for implementations of Nostr (e.g. some sophisticated library).

Another aspect is that the potential of Nostr has not even begun to be tapped yet. Most people seem to be using Nostr for micro-blogging, which is a trivial use-case. Maybe when the hype of micro-blogging wears off, Nostr developers will start looking for non-trivial use-cases for Nostr.