What would god have to lose by making himself known to a person who has simply concluded that he doesn't exist by using the very intellect this being supposedly created him with? God wouldn't have to lose anything. It is the imperfect men who would lose his freedom. And it is not a simple conclusion. The simple conclusion is God exist. Concluding that God doesn't exist takes a good deal of effort. It's like refusing to admit that you are in love to someone when you evidently is. It's possible, not an easy task but possible. It's even possible to hate that person if you wish to conclude that.
Luk, you have to understand that people are wired differently. Some might have a deep, inner need for spirituality and/or religion in their lives, else they feel adrift. unconnected, and unsatisfied. To them, the mystery and wonder of the world around them is so overwhelming in its complexity that they cannot conceive of there not being an intelligent creator. They naturally gravitate toward belief in a deity, and find their sense of comfort and belonging in that.
Others are wired such that they find immense satisfaction in the world of science and observation. Even if the details of how the universe and life within it came to be are as yet incompletely understood, they do not find fear and insecurity in that lack of knowledge. Rather, they find excitement at how much of that knowledge HAS been accumulated and continues to be constantly refined to fit together better and better. There is simply no need for a deity in the way their minds naturally respond to the world around them. Disbelief is NOT some sort of great task they undertake. It is simply the conclusion they reach.
Again, Luk, there is no willful denial going on. It's not a matter of someone refusing to acknowledge something which is actually there. In your example, someone convincing themselves that they are not in love with a person, but rather working to channel any bits of resentment against them into an active hatred. Yes, sometimes this happens (I have seen a couple of really messy divorces where that was seemingly the case). But all the people involved are real, physical, tangible entities with real, physical relationships. But as much as you, or some other believer, might feel that they have that kind of relationship with god, or even just that god's presence is something undeniably real, that is not true for everyone. It's quite possible to go through life without ever, once, having that sense. It's not a denial of god. It takes no more work and effort than it would take for you to steel yourself against letting faith in the Flying Spaghetti Monster gain a foothold in your mind.