The first thing I'm thinking is because of the listing fee that they can acquire from the particular owner of that coin. The more they list coins regardless of their intergrity, they don't care as long as they get the profit. The second thing that I'm thinking is that they believe that shitcoin could become a reputed coin just like other coins in the market who has a huge market cap whom just started from being a shitcoin. We can't really underestimate the potential of a coin as all of them can be successful once the demand overwhelmed.