You might be exposing yourself to man in the middle attack when you connect to free WIFI network in public places.As hacker can pose a free WiFi network by using his own phone as a hotspot luring you to connect to it as a result of it your personal files, phone and credit card details are all hijacked.
In a survey conducted by Cyber Security Agency of Singapore 6 out of 10 respondent connect to public places WIFI network even though they are unsure whether the connection is secured. 1/3 of them would even conduct financial transactions and online purchases on the network.
This would result that your sensitive information could be accessed by hackers to be sold on the Dark Web, a part of the Internet which is often used for unlawful activities and hard to access