My case is a bit more complex. Normally I take backups of my Bitcoin wallets, so there is no question of losing the access. However, I had accounts in a few cryptocurrency exchanges, which are now defunct. Wex.nz and Cryptopia are some of the exchanges in which I had account. When these exchanges closed down, I lost the access to my coins. And worse still, the amount was quite significant for me, at least in the case of Cryptopia.