Negatives are your originals, the prints or scans are the access copies. Scans, in particular, are very temporary unless you spend a LOT of money on backups and migration over time. Even if you spend a little money on cold storage for negatives, it’s more cost effective than tossing them after scanning.
Think of them as part of your collection – would you toss an item simply because it’s not currently on display? Because you have a reproduction? Or are these photos documenting conservation work that you need to keep?
Granted, not all photos or negatives are good – I tossed a lot of blurry long-distance shots of nameless teams playing soccer in nameless fields – but make your decision based on what generation it is (original or access) and what the content is, rather than space concerns.