Badd vs. Bad

Something that has always left me puzzled is why/how do guys (and yes some girls) deal with somebody (i.e date, talk to, hang out with etc.) who clearly sparks their interest, is compatible and hey, even easy on the eyes one minute, and then drop them for someone who is a absolute downgrade! I mean, its like going from a steak dinner to a chicken box! From a fine bottle of wine to a cranberry juice box. Now I'm not one to drag someone down but come on!!! What's the point of dropping a good match for you and leave them for something worse. Is it because they're easy? Not hard to work for? Sheesh better conversation? I don't know guys but really, whats the point. I'd rather have someone that's Badd then just someone that's Bad.