first of all i challenge you to do this challenge too!
Hmm now what i think about that eh. I don't know how or why but i don'y find pleasure on doing some outside ''things'' alone like drinking coffee for example. As you say you can drink it home with 0.10 what will be the difference in the cafeteria? ( i can't think of any argument except if you like the waitress/waiter :p ).
With friends and in general company you will say a few words, laugh and gain new experiences and that's for regular stuff. imagine who i will get bored if i go for hiking alone :p