In theory, these web3 platforms would still need to function as a business to continue existing. Moving the platform onto a blockchain removes the need for centralized servers, but it necessitates massive amounts of distributed compute power to keep it going.
Every blockchain project knows that they need to incentivize their miners somehow. This is usually a combination of fees from users and new tokens minted via built-in inflation (yes, inflation ironically powers much of the crypto space and will continue to do so for a long time).
So I always aks:
1) What problem are these web3 platforms solving?
2) Who are they solving it for?
3) Are those people actually willing to pay the blockchain premium to use a web3 platform over a centralized platform?
The theory, of course, is that blockchain will evolve over time to become less resource hungry and therefore cheap enough to compete with incumbents, but that's a long way away. Many projects have started cheating by smuggling centralization into their architecture but emphasizing their blockchain and hoping nobody cares enough about the difference.
But where do VCs come into the equation? They're not setting up the mining operations that will power these businesses and collect the fees in the future. They're investing in tokens that will ostensibly be used to pay the miners in the future.
The whole game is about introducing artificial tokens, quietly giving a huge number of those tokens to founders and early investors (in exchange for actual money, of course), and then hyping the platform to the moon so everyone can cash out their tokens to a new wave of speculators.