Grargar: Currently? Because of monstrous budgets. Take a look at the Tomb Raider reboot. Aside that, it would be a good idea to remind those companies that they are creating games and not an alternative to Hollywood.
This combined with unrealistic sales expectations. Consider the
Square Enix/Tomb Raider scenario, where the game shifted 3.4 million copies in four weeks, and yet still managed to miss targets.
Any market that can shift 3.4 million units in four weeks should consider itself lucky, but sadly the interactive entertainment sector is tainted by greed.
Not to mention that budgets are often inflated by inefficient management and ineffective company structures. The budgets often include payments to massively overpaid creative personnel (often voice actors), accommodate the need to pay the massively overpaid management board and shareholder dividends, and have astonishingly high administrative costs.