I've never had the experience of losing or forgetting a seed phrase, but I've seen other communities here who lost their seed phrase because they couldn't remember where they saved it. The other is because the PC desktop or laptop was hacked and they didn't save it on any USB flash drives.

Others are also careless; they don't think that the seed phrase is like a car key without which the car won't start. There must be a duplicate, so the same goes for the seed phrase; there must always be a backup.