LOL basic economics fail OP.  POW mining is exactly what gives bitcoin its value.  Miners have to expend real resources and fiat (or other value) to buy mining equipment and to run it, which they won't do unless they and other miners value those costs as lower than the amount of bitcoins they mine with them.  POW mining sets a base value for bitcoin.  That money you think "leaves the ecosystem" doesn't leave, it *sets the price*.
This argument has been debunked numerous times, I can't believe there are people still using it. There are many PoS eco-systems, just look at coinmarketcap.com. They have ZERO PoW, how come they have millions of dollars in value in their eco-system?
Bitcoin's value does NOT derive from useless PoW mining, that's ridiculous. If your theory were true, then if I create any altcoin, and put massive amount of ASIC mining it, then it should also have a matching value?
Saying Bitcoin purely derive value from useless PoW mining, is an insult to Satoshi Nakamoto, the developers that contributed to Bitcoin, and the Bitcoin community.