Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why would someone want to buy an option on the day of expiry
The short answer to your initial question is: yes. The option doesn't expire until the close of the market on the day of expiration. Because the option is expiring so soon, the time value of the option is quite small.  That is why the option, once it is 'in-the-money', will track so closely to the underlying stock price. If someone buys an in-the-money option on the day of expiration, they are likely still expecting the price to go up before they sell it or exercise it. Many brokers will exercise your in-the-money options sometime after 3pm on the day of expiration.  If this is not what you desire, you should communicate that with them prior to that day.