When Challenger exploded on launch January 28, 1986, the cause was quickly determined to be from a burn-through on the solid rocket booster caused by launching the spacecraft with frozen O-rings. Subsequent investigation showed that burn-throughs had happened before and concern raised, but the necessary changes were not made because of budgetary constraints, and because the prior burn-throughs had been relatively harmless. On Challenger, however, the burn-through from the SRB hit a major structural component, causing it to fail.
Now Columbia is gone, apparently from loss of heat tiles causes by a loss of insulation from the external tank. and once again we find that heat tiles have been lost on previous flights, as well as insulation from the external tank, and once again concerns were raised, but necessary changes were not made due to budgetary constraints, and because previous tile and insulation loss had been relatively harmless. On Columbia, the insulation from the external tank appears to have knocked loose a large number of tiles exposing a critical location to the heat of re-entry, causing the left wing of the shuttle to fail.
It was known a problem might have occurred at launch. But all of the tools built to deal with such a situation, to repair heat tiles in space, had been left behind. Budgetary constraints. It costs money to take along an extra EVA suit, the remote arm, and the tile repair materials, or the extra fuel needed to get over to the space station if something does go wrong.
7 people are dead and a national treasure evaporated, because someone looking at a budget decided you can pay for half a space flight and still get a complete mission. We've seen the same arrogance and stupidity before, in the men who decided to sail Titanic with fewer lifeboats, or that Hindenberg could be safely flown with hydrogen instead of helium while painted with powdered aluminum paint, or that Challenger could be launched knowing that the SRB had a tendency to spring leaks, especially when cold.
BUSH WARNED DISASTER WAS GOING TO HAPPEN