It is incredibly incorrect to think of light and truth as something that is set at birth, like one’s height or eye color. It just isn’t so. Rather than a static characteristic, your light and truth is more like how much money you have. It is about what you obtain, not what you start with.
In the parable of the talents, the Lord describes how and why it is that to those who have, he will give more (see Matthew 25). In the parable, two men are given more above what they already have because of their efforts to earn interest on what they have. By growing what they already have through their efforts, they earn the extra blessing and approbation of their master.
In the parable, their initial increase does not come from the master, who is away on business. It comes from the servant’s independent initiative. So where do they get it from?
They get it from other people, namely those who have it to give. God will give direct revelation to anyone who seeks it, but you can't completely control this through your own behavior. You can't force God to reveal something to you. However, you can seek light and truth that is already around you.
Our access to this light is limited only by our initiative. It is everywhere, just waiting for us to dig it out. We ought to assume that every person we meet might know something more than we do on some topic.
The difference between what we learn directly from God and what we learn through others is like the difference between gold nuggets lying on the surface of the earth, and flecks of gold dust embedded in tons of rock. Gold nuggets exist, but they are extremely rare. But you can mine rock as long as you have the resources to do so.
To mine gold you need to use the gold you already have to buy equipment, you need to expend the effort to dig it out of the ground, and you need to sort the gold from the much more abundant dross.
To mine truth, you need obedience to what you have already been shown, effort to seek out higher truth, and a willingness to test what you find.