How delusional is TOO delusional?

So I learned a lesson early on in my college career - Life is what you make of it. Specifically, I had learned from observation of a friend that you can color the world with the lens of your eyes alone, almost any color you want. Even more specifically, I had a friend, well acquaintance at the time, who believed that she had great friends who loved her or at least cared about her. Did it matter that these same "friends" of hers would make fun of her behind her back? At first I thought, Yes! it does! The truth ALWAYS matters. But then I observed how happy this friend/acquaintance was to live in her delusion. Why did it matter if her "friends" talked behind her back if in her presence they were perfect friends? My friend's delusion about the world around her served her well.

The same thing happens in dating. If a person believes they are hot stuff, though semi-objective measures (do these really exist), might indicate NO, people with self-confidence and high self esteem, no matter how unnattractive or unworthy of love can CONVINCE other people to love/like them purely based on their delusional beliefs in themselves.

So in a sense, delusion serves us well in subjective aspects of our lives, i.e. interpersonal relationships. Delusions are not, however, adventagous in more objective facets, i.e. careers or academia - SOMETHING has to be judged here and the product of the judgement is useful for the employer or the teacher. If you're doing a shitty job, you get fired. If you write a shitty paper, you get a D. But in relationships, if you think you're hot shit, you can always find someone to convince.

This is all well and good but, honestly, when is being delusional, even in subjective areas of your life, a bad idea? I'll tell you when. When being delusional is more a detriment to your growth and well-being it is then just hampering you and does not serve a good purpose. For example, if you think that rocking 80's hair and wearing cut-off jean shorts are hot and you can be as bad as you want to be, well take notice to your dating life. Have you attracted losers you wouldn't touch with a 10-foot pole? Well then I'd say you needed a smack back to reality. Another common example, that is just so utterly sad - women who believe the men they date DO actually love them when time, and time, and time, and time, AND time, again this guy has proven that his motives are not due to love but something else - convenience, obligation etc. Because for the umpteempth time, people who love you don't do X, Y, and Z. This is a clear case of delusion that does way more harm than any good - i.e. delusional person talks to friends ad naseum about boy or girl that no one cares about anymore; delusional persong goes into therapy thinking they are going to solve the problem but the delusion has clouded their vision for so long they don't even realize their delusion; delusional person stagnates for years on end in terms of personal growth and development b/c they're still hanging on to a person who has moved on.

So what is the solution to detrimental delusion? I'm not quite sure. But when I figure it out maybe I'll stop ignoring a current "delusional" friend and bitch slap her into reality..