This, of course, depends on the type of a firm. If a firm is a profit-seeking organisation, then its primary objective must be wealth maximization, a phenomenon by which the overall wealth of the shareholder is increased. Profit maximization is part of wealth maximization. It is necessary for the firm because:
A situation where it may be incorrect is, if the business is a not-for-profit organisation, then its managers must not focus primarily on profit maximisation, but their primary objective must be the care and goodwill of the people they wish to serve. Take, for example, a charity hospital, in a remote, low-income area. Its objective should be to provide quality health care at very nominal costs, to those who can't afford it. If it starts to charge premium fee for the services that it provides,no one would be able to affordit and its primary objective of serving the people will be simply killed in the process. Therefore, its managers must keep the noble objective of the betterment of the people in the forefront and the rest of the objectives such as profit maximization, market share, growth etc as secondary objectives.