custodial wallets don't fix this, you are just replacing it with another issue: "if the company is gone, your bitcoin is really gone too". and that is not the only issue, there is a new one too which is "if the company decides to shut YOUR wallet  down, your bitcoin is really gone".
this last one may not seem so serious because it hasn't happened to you yet but nowadays with stupid rules that these centralized services are starting to enforce (eg. coins that had a history of being in a coinjoin) you will be a victim sooner or later.