When it comes to buying things I like, I have certainly shown an impulsive streak. (I try to do "the research" for things like electronics, automobiles, and houses; but when there's no One Right Choice, I tend to lock up, flail, and choose based on fairly random criteria.)
On the other hand, I try to be moderate about starting an involvement with something. I poked around SGA fandom for a while before leaping into the deep end, and I've tried to be careful about just how far afield I take even that; I generally look for recommendations and reviews before getting into new narratives (movies, TV shows, webcomics, books, what have you). When it comes to actual physical involvement, I really tend to hang back. A lot of that is due to a collection of social anxieties -- for example, if I'm at any kind of gathering or event, I tend to feel lost and stressed if I'm not attached to other people I know. I only went to the past two Arisias because I knew I could hang out with good friends.
I also don't tend to just up and travel impulsively. I did spend one October weekend in San Francisco on what amounted to little more than a whim, but that was very atypical of me. I usually take trips only for specific reasons with much advance planning. (It doesn't help that flying is entirely too much of a hassle lately, with the Slapdash Security Regulations of Inanity and the occasional goose-in-the-engine event, and there's only so far I'm willing to drive, and trains take as long as driving while costing as much as flying, and my one long-distance bus trip Will Not Be Repeated.)
And yet ... I only just heard about Writercon a few days ago, and I'm seriously considering going. Even though, as far as I know, I won't know anyone there from RL, and so far I only even recognize two attendee names from SGA fandom.
Basically, I just plunged into a fandom for which canon just closed, and I haven't been this invested in something outside my Original Fic of Eternal Stalledness in years; this may be my only chance to meet like-minded folk before they drift off entirely into other fandoms that I'm not (yet) interested in. It sounds as if there will be a whole mess of "how to write" and "how to beta" panels and discussion. All of my writing-axis knowledge is self-acquired, from the dozens of "how to be a writer" books I absorbed as a teen and from years of reading books and (lately) fanfic -- I've been wanting a slightly more formal environment for a while now.
I'm pretty much trying to talk myself into it, I think. If it were in New England, I'd have registered by now, just because it sounds so cool. But when I add airfare and the whole "taking time from work to up and travel halfway across the country" ... it just seems both random and indulgent. It's not that I can't afford it; I just feel weird about it!
Then again, both violetcheetah and my mother are encouraging me to go. It sounds fun. I'll probably go. ... I think. (heh)