The idea of refusing when someone asks for a WiFi password may seem unacceptable but this may have consequences, so you must refuse, as the potential dangers extend from the individual visiting illegal websites under your IP address to the spread of malware to your devices, according to what I mentioned. British newspaper "Daily Mail".
If someone else uses your internet connection to download illegal content, they will leave a trail online back to your router, and you may be fined or possibly visited by the authorities.
If a device, such as a smartphone, is infected with malware and connects to your Wi-Fi network, it may continue to attack your computers, phones, and tablets as it spreads, and malware often runs in the background, which means that a person may be completely unaware injury upon contact.
Allowing someone to connect to your Wi-Fi gives someone access to a system where data goes in and out, and a technically savvy person can use free computer software that can scan your network and that will provide a list of every device currently connected.
While less risky than some of the other potential actions, someone using your devices over Wi-Fi can be frustrating.
Many people own devices such as printers, Amazon Alexa, speakers, and even hard drives that are connected to the Internet.
It allows users to control aspects of their home via their phones, but by sharing your Wi-Fi password, you are potentially allowing others to use these devices.
If you live in an apartment building or an area with a large number of potential Wi-Fi connections, handing over your password can cause problems.
If you share your password with one person, they can continue to share it with many other people, increasing the possibility of illegal activity via your IP address.