The only time you can forget your coin in your wallet is when you have small values of coin in that wallet, but a process whereby you have enough coins in your wallet, I believe that nothing will make you to forget the coin, even though the coin doesn't have relevant at moment, so it's not possible for crypto investor to forget it coin without target
Buddy it is possible to forget a coin in a wallet. It may not be intentional but either because of certain circumstances that makes you to abandon the wallet. If you have just little amount in the wallet that will be very small to withdraw especially considering the fee that you will use to withdraw it, you can decide to leave it there and by that, when it gets to bull season the coin can rise that you will be surprised how much the little money will worth. Yes, sometimes fees may be high for you to withdraw small amount remaining in your wallet and you can decide to abandon the wallet for a long time. So this is very possible and it is capable to increase its worth overtime. If you check your wallet and the withdrawals made 5 /7 years ago, you will see how much they are worth now.
Well we have not been in this space long like some of you guys who are the early adoptors most especially those that have been in the forum before 2017-2020 you guys saw the early entry of most altcoins even though you missed Bitcoin earlier stage where airdrops and bounties where still very profiting.
So possibility of having such left over coins, for whatever reasons are always there and we must acknowledge that fact.