Should I save dead quotes

Should I save dead quotes

I work in vehicle transport, specializing in transporting vehicles for dealerships. My role involves collaborating with individuals at each dealership to facilitate the transport of their vehicles to customers and from auctions. 

My question is whether I should save old quotes. By the end of the year, I could have around 20,000 quotes that didn't lead to any transactions. I’m concerned that keeping all this data might slow down my database. I would appreciate the community's input on this matter.