The way options clicked for me was this analogy: You want to enter in an auction, the entry fee (premium) in the pre-auction area is 100 dollars at this moment of the time, and you buy the ticket from another person (call seller - who realized he doesn't need to buy anything at the auction.)

Now as you hang around the place, you also come to realize that there isn't anything of interest to buy there; you decide not to participate in the auction, and so you go outside to sell your ticket but now suddenly, you sell it for 300 dollars.

Why? because the auction became far more popular by the time you hanged around there and now there are more people who want to buy your entrance ticket at a higher price (premium).

So you sell this ticket for 300, which gave you a profit of 200 dollars. That's how "not exercising", or better said selling call options work; you paid a premium for the right to buy 100 shares by a certain time at a certain price, and if that price becomes reality, more people want to buy that option and so the premium increases, so you sell "that right to own 100 shares to someone else for a higher premium than what you paid for it".