Why fake it until you make it?

I have heard this expression many years ago, and at that time, I understood it to mean 'Pretend to be who you want to be until you fool others to think you are , and you eventually become.' But I always knew there was something very unethical about pretending to be someone you are not, trying to impress others, or looking for validation. Why do you have to fake it? Why can't we just be?

Suppose you want to be a successful Hedge Fund Manager, faking it will definitely not get you somewhere if you are still working up the financial ladder. People don't become Hedge Fund Managers overnight, nor do they became successful without a lot of hard work, persistence, patience and all the other traits needed. So instead of using the expression 'Fake it until you can make it' why not use a more productive, authentic and ethical one, and say, 'Work hard, stay focused, network, and stay true to yourself and others, until you make it'? I like the following statement as it doesn't deny the importance of carrying yourself a certain way in order to attract the right things and people into your life, but it should be noted that this has to be done in an ethical, confident and graceful way, and not to appear to others like an imposter.