Nothing, literally nothing about web3 is a pyramid scheme. Yes you can build a pyramid scheme on top of web3. No web3 is not a pyramid scheme.
You can build a pyramid scheme on facebook too, but facebook is not a pyramid scheme.
You can build a pyramid scheme on facebook too, but facebook is not a pyramid scheme.
As long as it's centered around the value of BTC, this is false. BTC has totally failed as a currency and is completely dependent on speculators pushing its valuation up to keep the miners profitable. I'll be willing to concede this point to you if eventually all proof-of-work coins disappear and the BTC maxis go away, and the incentives change to move away from mining and towards providing real services, but I doubt this will ever happen given this was the whole reason the crypto bubble happened in the first place.
Perhaps you want to define web3 in a more vague way like "any web business that uses a merkle tree publicly in some fashion". You can do that but either you're still left with BTC maxis leading the charge on that, or you have to expand it in such a way that the term becomes meaningless because it applies to a lot of unrelated things. Was google a web3 business before anyone knew what that was because they used a merkle tree in google drive, and google drive was public? How about github with their public git repositories? See what I mean here?
Edit: typos
I used to be very interested in defi but I can't anymore when it's evident that the same market forces and consolidation and network effects keeping traditional banking afloat are also keeping BTC afloat because too many people are invested in keeping it the dominant coin. I really hope I'm wrong and BTC is not "too big to fail" but if I am then I expect you'll see these fancy web3 startups pivot back to making "boring" web 2.0 banking systems because there is no big money in defi anymore.