How small have you made yourself for others today?
When they see you, do they think, “This is someone who is secure with himself and therefore, he must not be a threat to me.”
Not threat as in bring physical harm to, but a threat to their identity. The bigger you make yourself — even if it is true — the more likely you are to show them what they don’t have. Unless they are self-aware enough, they will mistake their own cognitive-dissonance for a fault they would rather make up about you.
You can judge how open you can be with someone based on the identity they show you. The only people who will value a completely forthcoming conversation are other people who had the self-awareness to downsize their own identities. And chances are, they’re probably successful too.
But, if they are not, they will subconsciously mistake their own dissatisfaction with their lack of success for you being an arrogant, boastful asshole.
The bigger you make yourself, the closer you are to conversational suicide.
Would you like to help them correct these cognitive biases? Of course. But, unless they ask for your blunt honesty, they are best left to work it out on their own.
Whether it is tomorrow, on their death bed, or never at all, reason will always be waiting for them if they choose to see it. Unless they already have the will, your effort will be to no avail. And there is no time to waste on people like that.