The chance of checked luggage being stolen or damaged or taken by mistake or just disappearing is vanishingly small. But it does happen. If you cannot relax about it, you won't enjoy the trip.
Thus, checked luggage should not contain irreplaceable, expensive, fragile, or unique items. The airline’s Terms & Conditions will probably disclaim responsibility for these sorts of items in any event.
Checked luggage should contain only items that can be easily replaced. Remember that no matter where you're going (except, perhaps, to Antarctica), you will find stores and commerce.
Irreplaceable, expensive, fragile, or unique items should not be contained in checked luggage. Either bring them with you into the cabin, or ship them separately with appropriate packing using a reputable courier with package tracking.
In your cabin baggage (or on your person) should be your electronics, medicines for the entire trip, and travel documents, plus anything else that you’ll know you’ll want to get to during the flight. Many also carry an overnight’s worth of clothes and underwear in case of unexpected on-route delay.
Pre-covid, my wife and I regularly traveled for a month or two at a time with no hold luggage at all, each of us carrying into the cabin one small backpack and one small roller case. As Robert Browning and Mies van der Rohe and others have observed: less is more.