Sadly, most of these tombs have been looted and that looting likely took place not long after the burials did. It likely took several people to prepare the dead, build the tomb and bury the body... The treasure they buried with these bodies was obviously valuable stuff. So somebody involved with burial, and knowledgeable about it’s whereabouts and contents would likely raid it at some point.
That’s what makes Tutankhamun’s tomb so amazing... All that treasure and nobody ever looted it. Everybody involved in his burial must have died in some natural calamity or war. Otherwise, they would’ve looted his tomb at some point.
I had a dim memory of reading about an ancient attempt at robbery, but luckily refreshed it with a web search:
https://www.quora.com/Ancient-Egypt-Why-didnt-grave-robbers-loot-King-Tutankhamuns-tomb