Yet another domain

I just purchased yet another domain from godaddy (yes its still confusing). websiteown.com is the domain I purchased. I purchased this domain as according to google keyword tool this term get more than 350,000 searches every month.

So how actually I decide whether to buy a domain or not. I brainstorm about the domain name then I think whether I will search for that term on google or not then I think whether my wife (who is not much familiar with web) will perform a search on google if I tell her the subject I want to search then I go to google keyword tool and then look for the amount of searches that term gets. Then I think how much SEO I will have to do to make this domain rank well in search engine. And last and most important how much this domain can earn me or how many email subscriber this domain can attract. That's all.