It's like asking if the millions being spent on the current airport is a waste since it will be demolished in a few years when the new(er) airport is ready.

The only trouble with having lots of money slushing around an economy is the risk of inflation, but thankfully Qatar has the NOC to prevent people from getting new jobs with higher salaries. If they got rid of the NOC rule there would almost certainly be a wages spiral and inflation would be out of control.