Nothing in the world can protect you from poor hiring .
If the employees truly are corrupt then they would make more money selling the bug in the black market then to a legit bug bounty .
Again it should not be linked to value , I.e. not 100m , it should be linked to effort it will take for a security researcher to find it .
Let’s say it took 3 months for a 0 day , the payout should be in the range of 40-50 k dollars perhaps .
It is still not a good deal for the guy finding it , he is risking months and he may not find anything , however being fairly remunerated for the effort if not the value is the first step companies have to take and it won’t look like a cheap trick.