When I was younger, my friendships were mostly based on geography, ie, kids who lived near me, but with whom I didn't share many common interests. Same thing in college, but included others in my classes, ie, common experiences, but not necessarily common interests. Now I guess my friends do come from my actively pursued interest areas. But I can't easily mix friends from different interests (tried it, didn't work very well) and if I taper off an interest, the friendship fades. Since I simply do not like merely hanging out with someone, must instead be actively doing something, I have a pretty high rate of friend turnover these days. Frustrating, but I'm mostly resigned to it now.
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The plural of "anecdote" is not "data".