Your johnson is yours for life.
False: a man can lose his johnson, get a new one, or (usually) both. We all know famous examples of either of these scenarios, so I won't bother recalling them.
Your manhood is directly correlated to your confidence - no surprise.
I trust you've done "empirical work" with a representative sample of men to corroborate this claim? If not, where's a "firm" (no homo) indication that it is true?
Because man has always had only one purpose...genetic reproduction.
False: throughout history, men have dedicated themselves to a variety of purposes above and beyond procreation. This is easily demonstrated by the fact that men still pursue things, presumably purposes, after the procreative function is fulfilled -- to say nothing of the men who never procreate but still have purpose.
And no other masculine trait is more celebrated when it comes to genetic fitness than the "size of your boat".
False: the most widely celebrated masculine traits (putting aside the issue of what is and isn't inherently "masculine") across history have been behavioral: confidence, risk taking, assertiveness, leadership, etc. You're deluded if you think anybody -- man or woman -- concocts a list of "great men (qua men) in history" on the basis of cock size.
This continues to be true today, something which is readily apparent if you interact with women in a larger sample than the 'sloothoar' demographic -- try it sometime.
Of course, this isn't to say that biological (physical) traits don't matter. Surely they do, size included. We're merely speaking of primary emphasis here.
P.S. What evidence is there that penis size is an indication of genetic fitness?
Women may choose a rich man to provide for and care for their children, but they want a masculine man to create the offspring.
Literally millions of women -- far more than would ever want to mate with you or me even if they knew we had large wangs -- want to mate with some twink named Bieber; how does this fit into your theory of attraction?
Therefore, having it means always being confident in your genetic fitness as a man, even in abject poverty.
This doesn't follow from anything you've said, and is therefore an unsupported conclusion (despite the conclusion indicator 'therefore' suggesting an actual argument was presented).
The confidence money provides is illusory.
But the confidence derived from reflection on the efforts/abilities it took to acquire said money may be everlasting.
I think I've put this about as eloquently and "scientifically" as one can.
I'm afraid not.