Egoism type thing

According to almost every dictionary egoism is the habit of valuing everything only in reference to one's personal interest and it's connected with selfishness. Why? Why is egoism so bad? I believe there are few or at least two kinds of egoism. Great and bad(defined above). I know that loving ourselves, appreciating our skills and abilities is awesome and I regret that this idea came into my mind a bit late( well, it's never too late to learn something!).
You can't love the others without loving yourself. Make yourself happy and the others will be happy with you. Hating ourselves gives us only depression, bad mood and our lives are just creepy and sad.

Trust me, I know what I'm talking about. I hated myself for so long time for just.. everything! I was sad and depressed. Now I appreciate almost everything about me and I still work on my develop and I am happy, very happy.

Well, that's it. I just had to share it with someone. enjoy your day