I'm not sure I agree with the philosopher 100%, though he doesn't mention what form of gambling he studied, just seems to be gambling in general. I'd also guess that most pro gamblers when it was written very much kept themselves to themselves, so he could have been looking at people who span a small profit, but didn't pull a wage.
Anyway, a couple of points he missed (or weren't posted). Emotions become less with both aspects of the game as the fight feels less. I can't get 5% of my bank on anymore, even if I got family members/friends to open bank/bookie accounts and place bets, they won't entertain 5% of my betting money (maybe if I seriously spread it about between them, but that means settling for a portion of it at shitty odds). Thats my first point, once a level has been reached and you've become accustomed to that level it doesn't feel like you're gambling as much, the fight doesn't seem as intense (though obviously you still hunt the winners/value with as much passion) the rewards and loses on your labour are less, so a bit of apathy starts to creep in (in a financial sense).
Secondly, he missed out another part which to me is one of the nastiest emotions you have to deal with, and that is letting winners go by unbacked! If you can't control this, then you're screwed. The mug punter within you with his scatter gun approach would have had a great day/week, and as the days/weeks like that pass, it's damned hard not to 'get stuck in'. It is what separates the successful gambler from the average gambler in the long term. It's discipline, but being able to deal with applying that discipline while Lady Luck is continually kicking you in the nuts, is what makes the difference, and for me is one of the most awful feelings with betting. Now couple that with a disciplined losing run and emotions are at a serious low (which can bring in a serious amount of apathy towards the game in general). This is over the course of 2 - 3 weeks for me though, nothing to do individual winners and losers, and is really the only thing that gets to me now. I find it is almost self propagating once it starts as well. I actually think I tighten up in case I'm letting it get to me, then have to endure more winners going by unbacked, and the seeds are sown for the next day, vicious circle. It's been a few years since I last spat the dummy out and went in all guns blazing (disastrous outcome), so maybe I've mastered that now, but it doesn't feel that way once the losers start getting backed and the unbacked possibles are romping home at tasty prices. That last element of discipline can be soul destroying stuff, I've been close to tears with frustration at times.
Edited - Everyone is different of course, I can only speak from my experience and betting the way I do. I don't mind backing something EW at 16's for it to finish 7th, then watching it win a few days later at 20's, at least I can seek comfort knowing I was on the right track in the first place. I reckon the bottom line is simply 'keeping your cool' in all aspects of the game. Though a run of unbacked winners does get me hot headed at times.