To buy Everton out right i imagine its going to cost between 200-300 million, then you got to build a new stadium which will cost around 300-400 million to build once you brought the land, paid off any people who's house you need to knock down an build the infrastructure around it. so thats 500+mil you spent before you paid off debt an then started spending on the team.
The fact is that these Billionaire want instant sucess, they don't want to be messing around building stadiums. Look at liverpool, there stadium stop being built because the owners can't afford it anymore or can't be arsed building it because it cost to much money.
Having a new stadium makes Everton look better. The billionaire will look an think, well i only need 200-300 mil to buy the team then i can spend on the team