If Brexit is done properly, when stormy waters have calmed, it can most definitely benefit the UK economically, given that economic growth areas it can take advantage of are largely in India and other Far Eastern countries like Singapore, Indonesia, Phillippines, Malaysia, Pakistan (I exclude China because of political uncertainties).
Compare that with the EU which is pretty stagnant, and will take on more liabilities when countries such as Albania and Ukraine join (Note - the UK should, and I'm sure will, contribute to Ukraine's regeneration once the war is over).
Of course, Brexit advantages are more than merely economic, taking back control of important areas like immigration from Brussels and giving it back to Westminster.