I think you misunderstood my comment. Yes, the rich don't bid for everything, and yes it's because they can't. But that's still consistent with what cousin_it said.

The main flaw with your argument is that "if Rich Bob really can outbid Poor Alice for a glass of water, then why isn't the world actually full of dehydrated poor people?" is 1) a non-sequitur, and 2) doesn't make any sense because the if condition is false.