There are several functions. First, you can show off to others and satisfy your vanity. Second, you can collect it as a souvenir. Third, there are economic effects. If a celebrity's signature is rare and that celebrity dies, then this signature will be worth a lot of money. There have been such examples, such as the first American astronaut who landed on the moon, and his signature at that time could fetch a lot of money! Having said that, I hope the landlord will adopt it!