Again, you are strawmanning.
If your thesis is Monero "will decay like food" you don't have to stack Monero long term. You can continue saving in Bitcoin if you wish. It is not binary. There are major differences/trade offs between LN and Bitcoin on chain otherwise you would keep all your Bitcoin on LN.
Not only that, but people stack all sorts of things that decay in the real world. No one on the planet keeps 100% of everything they own in perfectly un-decaying assets. I'm sure you also own many things that decay for different value or utility besides savings (vehicle, food, cash, electronics).
You are very misinformed about Monero. You could do a quick search and find out in a few seconds that is not true. You are right that ring sigs are only obfuscation. You are wrong that it is the only thing Monero uses.
1) Ring signatures are ONLY for the sender. (and it is by default unlike Bitcoin coinjoins)
2) Confidential transactions (ZK proofs) hide amounts completely
3) Stealth addresses hide recievers completely
For privacy:
Monero >>> LN
1) You see virtually 0% Darknet Market adoption of Lightning where the lives of people hang on the line.
2) Even though there exists possibility of some privacy on LN with much hassle - How does 90% of everyone use it? Custodially with things like WoS (no privacy from custodian). The remainder use something like Phoenix for self custody (no privacy from ACINQ) https://phoenix.acinq.co/faq#how-private-are-my-payments-on-phoenix
3) Search any technical paper and you will find that Lightning was not built around privacy and has many problems. It's focus is quick off chain payments with privacy as an afterthought or happy coincidence. Here are a few links.
https://github.com/lnbook/lnbook/blob/develop/16_security_privacy_ln.asciidoc#attacks-on-lightning
https://lightningprivacy.com/en/introduction
https://abytesjourney.com/lightning-privacy/
