A call option gives its buyer the right, but not the obligation, to buy the underlying at a fixed price — the strike price — until expiry. A put option gives the right to sell at the strike. The buyer pays the seller a premium up front for that right, and the premium is the most the buyer can lose.
The clock is what makes it hard. An option's price is partly what it would be worth if used today and partly time — the chance the underlying moves far enough before expiry. That time value shrinks every day, and faster as expiry gets closer. If the price hasn't passed the strike by enough to cover the premium when the clock runs out, the option expires worthless and the whole premium is gone — even for a buyer who was right about the direction but wrong about the timing or the size of the move.
Right about the direction isn't enough. The move has to be big enough, soon enough.
Educational content only. It is not personal financial advice.