I understand your objection perfectly well. This isn't a question of how soon they turn a profit - it's a question of whether or not there's any development at all.  This is not the gravy train you've misunderstood it to be. 

The difference between tax breaks and incentives is the restrictions and qualifications they come with. If they're not well-balanced, we end up with Capstone. If they are well balanced, we have thriving city neighborhoods or districts that more than pay for the tax breaks once the tax break period is over. That sort of long-term thinking is why these tax breaks, if done right, pay off many times for tax payers. Unfortunately, much of the voting public reaches for the pitchfork every time they hear "tax break", no matter how unequipped those members of the public are to understand the larger picture.