Being the owner of a team is one of the most difficult jobs in the sporting industry. Every decision that is made within the team is run by the owner and needs their approval to move forward. When a general manager makes a trade, or a coach makes a personnel change this was not done without the explicit approval of the owners. This is added on top of the other tasks an owner holds which focuses on the financial side of the organization.
So, it easily can be considered one of the most time-consuming and stressful jobs, and yet many owners across sports leagues choose to own multiple teams.