its also worth noting and people need to accept the risk that their funds are no longer 100% theirs in a channel.. its not a sole holder bank account. its a joint account. because it requires the other person to agree on what you want to do with "your money".
.... only the time of lock out and a fee. You can always unilaterally settle a channel, only your funds will not be available to you for a pre-fixed time, say, a day, or a week (100 blocks, 1000 blocks), which you agreed upon when you opened the channel.
If I put 1 BTC in a channel with Joe, and Joe also puts 1 BTC in that channel, and we agree when we do that, that the lock-out time is 1 week, and then Joe goes fishing and I never see him again, I can get my bitcoin back by settling, all by myself. But I will only be able to use my 1 BTC again next week. And I'll be the one paying a fee.
That remains true if I bought first something with Joe. If I buy fishing gear from Joe for 0.25 BTC, and Joe and I do a LN transaction, updating our channel (for that, Joe has to interact with me ; if he doesn't I cannot send him 0.25 BTC over the channel), I now have the new state, and if Joe goes fishing at that point, I can settle unilaterally in a 0.75 / 1.25 ratio. After a week, the 0.75 BTC minus fee are mine and Joe has his 1.25 BTC if he wants to. I don't need him to do anything for that.