@Beth394 When a guest asks for a discount, they are asking for you to make a special exception for them. This type of guest usually ends up acting entitled in other ways as well. Many hosts have found themselves bending over backwards to try to accomodate these types of guests, which the guests don't appreciate- they feel they "deserve" special treatment, and usually they will never be satisfied. Therefore, even when you try to make sure they are pleased, nothing will ever be good enough for them, so they leave bad reviews anyway. They're just complainers by nature.
Hosts price their listings taking into account the going rate in their area for what is provided, how many guests they can accommodate, what amenities they provide, etc. It's not just a number pulled out of a hat. So when a guest asks for a discount, they are basically disrespecting you and your listing. The 20% discount is used by some hosts to get the first guests and a few reviews under their belt, after that, you should stick to your listing price and all your other fees. There's no reason for you to be concerned about your guests' travel budget or finances. There are plenty of listings out there for all price ranges. I'm sure these people don't go into a restaurant or Starbucks and request a discount.