Why do these people do this?

This seller had a great review, I bought a jumper from her and in her description she mentioned she ships out the same day if possible. 3 days went by, I messaged her. Nothing. I assumed she could’ve had family emergencies or any other reasons she couldn’t messages back so I didn’t want to bother her, and out of curiosity I wanted to see what else she was selling and to my surprised she posted probably 50 items after I bought her item. She typed in description and seem like she had time just to replied me back and I’ve messaged her few times, still nothing. So I had to “pretend” I was another buyer and asking if her other item was available and she replied instantly. Literally not even 5 minutes, and praise the lord she cancelled it but at the same time… why did she do this? The jumper item never shipped. She ignored the crap out of me for almost 2 weeks, I’ll never understand these people! Ugh.