there's just one thing i want to add which may in some case all every case contradict the sentence you said like - " if a billionaire want to sell his all shares lets say his net worth is 100 b usd , due to supply and demand thing they may never get that 100 b in their account as liquid money but there are few scenarios where people ( even some billionaires ) have sold their whole companies to another billionaire or billion dollar companies and they got to keep lumpsum amount in some case even at slightly higher value or less value " real life examples - elon sold paypal , private equity companies , vc companies , elon bought twitter etc .