highly recommended

Live life for your benefit- the selfish gene, the truth of us we all do not accept. Misunderstood. 

Nurturing the ego is not what taking good care of oneself constitutes and the satisfaction of the primal urges would lead to a bizarre evolution, as it is plainly visible within society. We have a lifestyle that's fucking irrational. As far as one may argue doing what nature dictates is always healthy, we must not disregard that ill behavior is so successful because we cannot discern it from the healthy and natural. 

"It is the truest and most right, because it is sincere." 

No. "Sincere" - is it only one thing, is it only the easiest way for you? Sincerity is not something familiar to mankind and we abuse it, because as you may honestly want to harm another, you might simultaneously desire this only because of the greater wish to be a bigger and more valued person. Self-discontent is a source of evil like any other and its projections may be rather elusive. What a positive egoistic behavior would be is self-development even at the expense of social life and bonds, material belongings, leisure time. Most people would understand egoism as mercilessly placing your immediate needs ahead of those of others, even as parasitism, but short-sighted egoism easily proves destructive. Placing your evolution over maintaining certain social positions and attending to every little mundane need (those of your own and others for personal gain), in the case of successful development, will be fruitful for both yourself and society and assure a level of satisfaction and peace. Working on the mind and the body must not be neglected for immediate satisfaction of the mind (for entertainment) and body (for consumation/play).