I wonder if there's anything unique about your situation or just a lot of bad luck. Are you buying generally higher-end items? What does the tracking reveal in terms of where in the process the item disappeared? In the US or China? Or was it just never tendered for delivery?
I've bought a lot of stuff from China on ali and ebay, but no single item over $30 in value. So far I'm at 100% in terms of delivered items. A lot of crushed packaging, but no damaged items. Maybe 95% in terms of on-time delivery.