Beyond millionaires who already had large wealth unassociated with Bitcoin, you're unlikely to find many people who are flaunting their wealth. People with money who worked hard for it generally have the sense not to advertise it, because wealth breeds jealousy and it will make them a target for all sorts of different people. Most of the biggest wallets are likely to belong to exchanges or other large crypto related sites, so there is not much use trying to find all the largest wallets if you want to connect them with particular individuals. Any wallets connected with criminal activity are often worthless because to convert it back to fiat currency often exposes the people behind it.