Here is an article that goes some way to showing that the more private the data, the more attractive it is to attackers.
Infidelity site Ashley Madison hacked as attackers demand total shutdown
Site’s hackers claim 37m personal records have been stolen from notorious dating site, with Cougar Life and Established Men also compromised
Hackers have stolen and leaked personal information from online cheating site Ashley Madison, an international dating site with the tagline: “Life is short. Have an affair.”
The site, which encourages married users to cheat on their spouses and advertises 37 million members, had its data hacked by a group calling itself the Impact Team. At least two other dating sites, Cougar Life and Established Men, also owned by the same parent group, Avid Life Media, have had their data compromised.