Yes, your understanding is correct. LN is indeed an investment, not very risky, not very profitable, but useful to learn the ropes, people and tech. The biggest risk is losing your node due to hardware failure so make channel backups regularly. Best to automate it with Restic for example, it's easy to setup with virtually any storage, SSH/FTP/S3/WebDAV/etc. and it's FOSS. In case your node dies you can use that small backup file to force close all your channels by asking your peers nicely to do that for you. It's the only supported way to recover your sats, NEVER backup the big channel database. If the state there is outdated even by 1 step you will get punished by your peers and they will take all money to themselves because you'd use a revoked state.

Nothing is guaranteed with LN (in terms of profitability and availability) except the fundamental principles and it's by design. If it weren't possible to unilaterally take your money back while making sure each participant can only get back what belongs to them and not more, LN would be just another trusted exchange of sorts. If you believe no one ever tries to cheat and everyone is always online, the protocol could be 100 times simpler, just update the balances internally, no revocation needed, no HTLCs etc.

Force close is what makes it work, and it's the nastiest thing at the same time. Probably my most love-hate feature, love that it exists, hate when it actually happens to me. If we were only able to close cooperatively it'd be a disaster, because your peer could disappear and you'd be left holding the unusable bag. Maybe they would do that deliberately to mess with you, especially if the balance is on your side mostly so their loss isn't significant.

Another aspect is that nodes can refuse to accept your channels no matter what (by public key or IP for example), and it's their right. Fortunately, you can connect to another node and as long as you have any access to LN and liquidity you can transact with any node, and they can't refuse your payment because they don't know where it comes from thanks to the onion routing protocol.

I think these features let everyone have agency over their decisions, and at the same time limit that agency only to their own channels and not the entire network.