Why is craigslist so addicting? It's like I find something then I find something better on craigslist.com?

I am not advertising, I am just saying like one day I buy a puppy the next they are giving it away for free and it's a bummer. Certain situations you know. You can trade reptiles for ipods, and stupid stuff. Addicting and I am wondering if I should get into the craigslist/recycler business to sell/trade off some of my junk. Like kind of a free for all trade and sell flea market kind of no holds bar, no rules having, online frenzy. It is literally insane and I like it. Will these online sites take over local businesses in the future I am interested and I want to join when I am older.