There is always someone that will take advantage of a free situation. My daughter recently was living in an inner city highrise apartment block and noticed that shortly after logging in, her computer internet connection would slow dramatically. After lots of checks and diagnostics, she discovered a lot of university students would wait until they found an unprotected wireless connection and then would surf or do whatever they wanted to do without risk of exposure. She discovered at least 7 were hooking in to her connection.

 She very quickly added some software to block them because you don't know if they are setting up scripts to monitor your computer for internet banking or to read your confidential emails, etc. She is a specialist lawyer that requires a lot of after hours work, so naturally privacy is an issue.

From your point of view, whilst it is noble of you to support others that don't want to indulge by paying for their own bandwidth, but I suggest you are certainly leaving yourself open for cyber attack in some form.

Charitable donations may be more meaningful via with other pursuits.