It turns out that being in a virtual world really does make people happy. Edward Castronova and Gert G. Wagner have published a paper in Kyklos (Vol. 64(3) August 2011, pp. 313-328) that presents real data that shows that "among Second Life users, satisfaction with their virtual life is higher than satisfaction with their real life", and "that people in certain life situations, such as unemployment, gain more life satisfaction from 'switching' to the virtual world than from changing their real-life circumstances."
I've been saying right along that one of the biggest benefits of doing education in SL is that (after one gets over the newbie period) it's just plain fun. If you do it right, a virtual world experience can make you happy, and happy students learn more.