View it has a geometric series and not as a total bitcoins issued at any point in time. A geometric series sets a moving upper limit.

Because we don’t care about how many Bitcoin’s actually exist as much as we care about there being fewer than the expected amount.

Loop has the best article on it IMO for more context and I’m paraphrasing his work here. But understanding the geometric series is an important part of getting it. He does a good job of breaking it down.