Have you noticed that American society can be very critical about people spending time alone? Let's consider Friday night activities. The societal "coolness" factor of pursuits is directly proportional to the number of people involved:
1. coding at home alone
2. watching a movie at home with a friend
3. going out to the movies with 5 friends
4. going out to a house party with 50 attendees
5. going to a nightclub packed with 400 people dancing
Many people would rank these as ascending in coolness, i.e. descending in lameness.
I imagine that evolution rewarded sociable people who worked with others to build grass huts and hunt buffalo together, and that turned into a societal bias toward social interaction. But you'd think the sweet spot would be interactions of small groups, rather than enormous gatherings that are inefficient.
This rule can be broken with the inclusion of romantic partners. Watching a movie with a date is considered more cool than going to a house party with 50 attendees. This is presumably because evolution also rewards procreation, thus any overtures in that direction are also blessed.
UPDATE: Another aspect of this contemplation is over why society expects people to be social on particular times of week, e.g. Friday and Saturday nights. It's fine to read the newspaper alone on Saturday morning, but much less acceptable to do that on Saturday night.