According to whattomine.com, with an electricity cost of $0.03/kWh your cost is about 2/3 of the Bitcoin reward. Combined with a 10X higher reward, that means a Bitcoin miner with that electricity cost gets about three times as much return on investment, as a percentage basis, as an Ethereum staker. That's money they can reinvest in new mining equipment.
So you think the stock market is a ponzi scheme? Shares pay dividends, you are insentivised to keep putting money into the system
Only if you invest in the IPO or later stock offerings directly from a company. Otherwise you're just buying in the secondary market and no part of the price you pay goes to the company.
Crypto only has investor participants. You cannot ever get more money out of a Bitcoin than someone else puts in buying Bitcoin. Less, actually, because you have to pay miners to operate the network.
Stocks as a whole are positive-sum due to the contributions of non-investor participants.
Futures, options and PoS crypto are zero-sum.
PoW cryptos are negative-sum due to the contributions of miners.
In Proof-of-Stake, you are incentivized to keep your money into the system so you can control more and more of it. It's like a ponzi scheme where you are incentivized to re-invest your winnings. This falls apart when everyone starts to cash out.
The use of bitcoin mining as indoor heating is one such example of a dis-economy of scale (but this is an oversimplification because it does not factor depreciation costs). Also, there are systems like RandomX which encourage CPU-based mining, which has economies of scale for home miners or botnets over larger mining operations.