That's true, but PoW currencies have the same opportunity cost -- if you buy Bitcoin you can't invest the same funds else.

Let's say you were forced to invest all your savings in either a PoW or a PoS currency; no other investments are possible. Say they both have the same block reward, which is essentially inflation tax.

Since you'll have to pay inflation tax either way, wouldn't you rather invest in the PoS currency, where the tax is redistributed to stakeholders including yourself? Rather than the PoW currency where the tax goes toward hardware and electricity bills.