On blood substitutes, I'm having trouble finding that. Blood is mostly water, adding more hemoglobin could accomplish the same ends.
If this were the case, your body would be doing it all the time. Yes, people's bodies in higher elevations do, or people who stress their cardiovascular systems more (probably), but there's a reason why it isn't
everybody's body doing it; there's cost involved. It isn't free.
Artificial legs are more capable than their human equivalents. You can run faster, and without tiring ankles. But nobody ever wants to replace their legs.
This is quite bullshit. Even if you can sprint on a track in a straight line faster, artificial legs are nowhere as versatile or useless as the ones you develop naturally. You use your legs for more than sprinting on a hard, level surface in a straight line.
Your rat-race style video game is no better or worse way of frittering away your time than a sandbox type game, the only difference is that you're satisfying different hardwired desires, nothing you do in either of these games is bettering your position outside of it.
Categorically wrong. Even non-human animals play, and for good reason. We play games, and play with toys, in order to develop skills, including abstract skills such as problem-solving, hand-eye coordination, organizational thought, reacting to new situations, and so forth. Playing games is useful outside of the context of the game, unless you're playing the game past the point where you're getting anything new out of it and you're just doing it as an addictive/compulsive behavior, which was exactly his point.