There are risks, you need to remain online to catch your counter-party cheating. There are ways to outsource this to so-called watchtowers. This can generally b

There are risks, you need to remain online to catch your counter-party cheating. There are ways to outsource this to so-called watchtowers. This can generally be done privately, and the watchtowers generally get to take at least some of the cheater's money. I haven't heard of any successful malicious channel theft. I have read quite a few stories of people losing local data making it much harder to recover the money in the channel.