Yes. You have to have an overall advantage (positive expectation) on your trades. No money management scheme or mastering of one's mind/psychology will make anyone a winning trader or gambler if they do not have a worthwhile advantage on their bets. Examples: A. Every dollar bet is on average worth 1.01 B. Every dollar bet is on average worth 1.00 C. Every dollar bet is on average worth .99 Only the first example is positive expectation; aka, having the advantage, the best of it, being paid more than the odds, being paid more than is fair, etc.
That is good to see that, there are many books on trading but really do not understand why people right on books, if they are good on trading, why they just don't focus on trading and earn money.