Because these people represent a minority of the overall public. Yet they are exercising disproportionate control over critical government decisions. They have a right to their opinions and to represent those who voted for them. However, they've found a procedural tactic to put our society and the world in general at financial risk so that they can ram their beliefs down the throats of the majority. These people made promises that don't stand up to the real world. I don't really mind and often expect this from politicians but it is scary when people care more about re-election than maintaining the financial credibility of the United States of America during one of the greatest recessions in history.
Everything that you said could be used, word for word, to argue against the Democrats pushing through what many now call "ObamaCare". Based on opinion polls, a majority of American voters was against this change. Procedural tactics were used to squeeze the legislation into something that could get enough votes to pass, and out-right bribery in some cases (See "Louisiana Purchase"). The promises made to the elderly through Medicare don't stand up the liabilities we now owe. The debt incurred by these changes is perhaps not as great a financial risk as defaulting on the debt, but we've yet to see just what will happen if it does. You could easily argue that those voting in favor cared more about re-election (or were retiring and hence wouldn't be held accountable in an election) than ensuring financial stability in the US.
Your language could also apply to a number of other causes, though we'd stretch the "financial risk" side in doing so: Environmentalists, Defense Hawks, Warmongers, Unions, Corporations, "Big" Industries, Wall Street, etc. All of these in some fashion end up "ramming" (and jamming) things through Congress and down our proverbial throats.
What you want, but don't yet know you want, is more limited government. Take the power away, and the abuse of that power is also removed. If that power remains in Congress, it will be abused in Congress.
