I'm sure the happiness of people decreased over the last 10 years, but I believe that it's because of the bigger division between rich and poor people.
Personally I'm not a fan of Facebook, as I saw my home city (Budapest) becoming from a nice livable city to a tourist destination / loud party / get drunk fast city between 2008 and 2010 (and it hasn't gone back), and I believe Facebook took part in that (of course later AirBnB helped, but AirBnB was much smaller in that point).
As for other effects, like making people less connected in real life, and more through computers, it has good and bad side effects, I'm torn whether things got better or worse. (Also I don't post too often to Facebook, so I'm not a good person to judge it).
Personally I'm not a fan of Facebook, as I saw my home city (Budapest) becoming from a nice livable city to a tourist destination / loud party / get drunk fast city between 2008 and 2010 (and it hasn't gone back), and I believe Facebook took part in that (of course later AirBnB helped, but AirBnB was much smaller in that point).
As for other effects, like making people less connected in real life, and more through computers, it has good and bad side effects, I'm torn whether things got better or worse. (Also I don't post too often to Facebook, so I'm not a good person to judge it).